By the end of this lesson you will be able to
- Match common symptoms to the component most likely at fault.
- Explain the safety risks of static electricity, liquids, batteries and mains power.
- List safe things a beginner can do, and jobs that need a technician.
- Describe what to do straight after a liquid spill.
- Explain why a warranty matters before anyone opens a device.
Sooner or later something goes wrong with a computer. Good beginners are not the ones who repair everything, but the ones who know what is safe to try, what to leave alone and how to describe a fault clearly. A well-meant repair can turn a small problem into an expensive one, and some parts can cause real injury. This lesson gives you a safe set of limits and a calm method.
Common faults and their usual causes
Remember the four jobs and the parts you have met. A fault shows up as a symptom, and the symptom points towards a likely part. A symptom is a clue, not proof, and many are caused by software, so always try a restart before you decide that hardware is at fault.
| Symptom | Likely cause | Safe first step |
|---|---|---|
| Nothing happens when you press the power button | Flat battery, faulty charger or socket, or a power fault | Check the socket and charger, leave it charging for 30 minutes. |
| Power light on, screen black | Dim screen, loose cable on a desktop, or a display fault | Turn the brightness up; on a desktop check the monitor cable and power. |
| Very slow, loud fan, hot base | Blocked vents or a full RAM | Use on a hard surface; close programs; restart. |
| Clicking noises, files will not open | Failing hard disk | Stop using it, copy off what you can, ask a technician. |
| Picture flickers, lines or odd colours | Display or graphics fault, loose cable | Restart; check any cables; test on another monitor if possible. |
| Battery drains in an hour or the base bulges | Worn or damaged battery | If bulging: unplug, stop using it and get it replaced. |
| Some keys do nothing, or a USB port is dead | Dirt, a faulty key or a damaged port | Restart; try another port; gently remove visible dirt with the laptop off. |
- No power or lightsSuspect the charger, socket, battery or power circuits.
- Slow, hot and loudSuspect blocked vents, cooling, or full RAM.
- Clicking, unreadable filesSuspect the storage drive.
- Flickering pictureSuspect the display, its cable or graphics.
Read this figure as text
Four cards linking symptoms such as no power, slow and hot, clicking noises and flickering picture to a likely part.
No power or no lights: suspect the charger, the socket, the battery or the power circuits. Slow, hot and loud: suspect blocked vents and the cooling system, or full RAM. Clicking noises and unreadable files: suspect the storage drive, usually a failing hard disk. Flickering picture or stripes: suspect the display, its cable or the graphics.
Four safety hazards
Static electricity
Static electricity is the small spark you sometimes feel from a door handle. It is harmless to you but can silently damage computer chips. This is another reason that opening a computer is for people with training and the right equipment.
Liquids
Water and sugary drinks inside a laptop can short-circuit parts and corrode them. Keep drinks away from the keyboard. If a spill happens, speed matters more than anything else; see the steps below.
Batteries
As covered in the power lesson, the lithium-ion battery in a laptop stores a lot of energy. A damaged battery can overheat and catch fire. Never puncture, bend, crush or burn one.
Mains power
Mains power can kill. The power supply inside a desktop can hold a dangerous charge even when unplugged. Never open a power supply or a charger. Do not use a charger with cracked or exposed wires, and keep cables away from water and from places where they can be tripped over or crushed.
- Step 1: UnplugCharger and cables
- Step 2: Switch offDo not wait to save
- Step 3: Tilt to drainLike an open tent
- Step 4: Dab dryNo heat, no shaking
- Step 5: See a technicianSay what spilled
Read this figure as text
A flow of five steps after a spill: unplug, switch off, tilt to drain, dab dry, take to a technician.
Step 1: unplug the charger and any cables straight away. Step 2: switch the laptop off by holding the power button; do not wait to save. Step 3: tilt it like an open tent so liquid drains away from the keyboard. Step 4: dab the outside dry with a cloth; never use heat. Step 5: take it to a technician soon, say what the liquid was and do not switch it on first.
What you can do and what to leave
- Restart the computer
- Check cables, sockets, charger
- Try another port or cable
- Wipe outside with a barely damp cloth, power off
- Use a hard, flat surface
Low risk, easy to undo.
- Opening the case
- Replacing battery or screen
- Cleaning inside the fan
- Opening a charger or power supply
- Recovering from a failing drive
Can harm you or the device.
Read this figure as text
Two columns: safe things a beginner can try, and jobs for a technician.
Safe for a beginner: restart the computer; check cables, sockets and charger; try another port or cable; clean the outside of the laptop and its keyboard gently with the power off and a slightly damp, not wet, cloth; move the laptop to a hard surface; close programs; check settings. Leave to a technician: opening the case; replacing the battery or screen; cleaning inside the fan; touching a power supply or charger internals; any drive that is failing and holds important files; anything that smells of burning.
A calm method for any fault
- Stay calm and stop what you are doing. Do not press random keys or try several fixes at once.
- Write down exactly what you see, including any message word for word, and what you were doing just before.
- Save and back up anything important if the computer still works.
- Try only the safe steps from the table: restart, check cables, try another port, move to a hard surface.
- If the fault remains, or if any of the danger signs appear, stop and ask a technician or the shop. Give them your notes.
Common mistakes
✖ Instead of: Drying a wet laptop with a hairdryer or by leaving it on a radiator.
✔ Do this: Heat can damage parts and push liquid into places it has not reached. Unplug, drain and take it to a technician.
✖ Instead of: Trying several fixes at once when something goes wrong.
✔ Do this: Change one thing at a time and write it down. Otherwise you cannot tell what helped or what made it worse.
✖ Instead of: Opening a laptop or charger to look for the fault.
✔ Do this: Leave opening to a technician. It risks static damage, injury, and the warranty.
If something goes wrong
- I cannot decide whether a fault is hardware or software.
- Restart the computer, then see if the fault appears at start-up before the desktop loads. Faults that appear straight away or in every program are more often hardware. Faults in one program are usually software.
- A key on my keyboard sticks or does nothing.
- Shut down, unplug, and gently wipe around the key with a barely damp cloth. Restart and test the key in a text editor. If it still fails, ask a technician, or use an external keyboard in the meantime.
- I spilled a little water but the laptop still works.
- Treat it as a spill anyway. Unplug and switch off, drain and dab dry. Do not use it until it has been checked, because corrosion can appear days later.
Key terms
- Static electricity
- A small build-up of electric charge on your body that can jump to metal as a spark.
- SMART status
- A built-in health report that a drive keeps about itself, which software can read to warn you of trouble.
- Mains power
- The high-voltage electricity from the wall sockets in your home.
- Lithium-ion battery
- The rechargeable battery type used in nearly all laptops and phones.
- Power supply
- The part that changes the electricity from the wall into the lower, steady voltages that the computer needs.
Practise it for real
Reading is not the same as being able to do it. Complete these on your own computer, then tick only what you have actually done. These ticks are your own honest record: nothing checks them for you.
Write a clear fault report
Imagine your laptop will not charge. Write a short report as if for a repair shop: what you saw, what the charger light did, what you tried (another socket, another port), whether it ever worked, and any damage you noticed. Use fictional details if you prefer; do not include any real passwords. Check it for facts and for guesses, and mark which is which.
Challenge: give your laptop a safe outside clean
Shut the laptop down and unplug the charger. Wait until it has cooled. With a soft, dry or very slightly damp (never wet) lint-free cloth, wipe the screen gently and the keyboard surface. Use a dry cloth for the vents and ports and do not push anything into them. Keep liquid away from openings. Switch it on again and check that it works. Then list two things in this task that you chose not to do, and why.
Knowledge check
6 questions. You need 80% to pass. Mistakes here are part of learning, and you can retry as often as you like.
Summary
- Symptoms are clues to a likely part, but always restart and check the simple things first.
- Static, liquids, batteries and mains power each have real hazards. Never open a charger or power supply.
- After a spill: unplug, switch off, drain, dab dry, and take it to a technician.
- Beginners can restart, check cables, try other ports, clean the outside and move to a hard surface.
- Check the warranty before any repair, and write clear notes about what you saw.
Checklist: can you do these?
Marking a lesson as read does not prove you can do it. Skills count as demonstrated when you pass the quiz (not yet) and complete the practical tasks (not yet).
Related lessons
References and further reading
Official sources for details that can change between versions.
- Ubuntu documentation (Ubuntu)
- Windows support (Microsoft)