What to Check When a Computer Will Not Turn On

First, decide what “won’t turn on” really means

People use the phrase for two quite different situations, and the checks differ.

• No power at all. Nothing lights up, no fans spin, no sounds. This is a true no power fault, and it usually involves the outlet, cable, charger, power supply, or the power button.
• Power, but nothing useful. Lights come on or fans spin, but the screen stays black or the machine stops before it finishes starting. This is often a display, startup, or software issue, though it can still be hardware.

Spend a minute noticing which one you have. Listen for fans, look for any small light on the case, keyboard, or charger, and feel (carefully) whether anything seems warm or vibrates.

Start at the wall

Work from the outlet toward the computer, one step at a time.

1. Test the outlet. Plug in a lamp or phone charger you know works. If it does nothing, the problem is the outlet or a tripped breaker, not the computer.
2. Check any power strip. Make sure it is switched on and that its own light, if it has one, is lit. Surge protectors can wear out or trip, and plugging the computer directly into a working wall outlet is a quick way to rule one out.
3. Reseat the cable. Unplug the power cable at both ends and push it back in firmly. Look for bent pins, scorch marks, loose fits, or cable damage. Do not keep using a cable that looks burned or frayed.
4. Try another cable. Many desktop computers use a standard power cable that is shared with other devices. Swapping in a known-good one is an easy test.

Desktop computers

Once the outlet and cable seem fine, look at the machine itself.

• The power switch on the back. Many desktop power supplies have a small switch near the cable socket. It may have been bumped to the off position.
• The front power button. Press it once and hold for a moment. A button that feels stuck or does not click back may be faulty or blocked.
• Unplug accessories. Disconnect USB devices, extra drives, and anything else not needed. A shorted or faulty accessory can sometimes prevent startup.
• Check the monitor separately. Make sure the screen has its own power and shows a light. A dead monitor can look like a dead computer.
• Listen and look. If fans spin briefly and stop, or there are repeated beeps, note the pattern. The maker’s manual may explain what the beeps or lights mean.

If the checks above do not help, the next steps involve opening the case, replacing the power supply, or reseating memory modules or other internal parts. This is where many people should stop and consult the maker’s official instructions or a qualified technician. Always unplug the machine and wait before touching anything inside, and do not open a power supply at all, since it can hold dangerous charge even when unplugged.

Laptops

Laptops add the battery and charger to the list.

1. Check the charger’s connection at both the wall and the laptop. Many chargers have a small indicator light, though some do not.
2. Look at the charging port. Lint or damage can stop a connection. Do not poke inside with metal objects.
3. Charger wear. The cable near the plug is the most common failure point. If you need a new one, read about choosing replacement chargers so you get a compatible, safe match.
4. Try a different outlet. Do this with the battery connected and then, if the laptop allows, with a known-good charger.
5. Let a low battery charge. A laptop with a very depleted battery may need to charge for a while before it shows any sign of life.

Read the indicator lights

Small lights are some of the best clues you have.

• No light anywhere. Suggests no power is reaching the machine, or a failed power supply or charger.
• A light, but no fans or screen. Power may be reaching the computer, but it may not be starting properly.
• A blinking or colored light. Many makers use patterns to signal faults. The manual or the maker’s support site is the place to find what yours means.
• A light on the charger or power brick. If it is off while plugged in at a working outlet, the charger may have failed.

Write down what you see. A note such as “amber light blinks three times, then stops” is far more useful to a support person than “it’s dead.”

When it starts but shows nothing

If you can hear fans, see lights, or hear the usual startup sound but the screen is blank, treat it as a different problem. Check that the monitor is on, the right input is selected, and the cable is firmly connected at both ends. The guide on no-sound or no-display problems goes through these checks in detail, and the list of display cables explains which connectors do what.

If the computer starts and then shuts down quickly or reboots over and over, that is a separate pattern, often related to heat or power, and is covered in the article on random restarts.

When to ask for help

If you have tested the outlet, the cable, and the charger, and tried the power button and indicator lights without any sign of life, the cause is probably inside the machine. A failed power supply, motherboard, or battery is possible. At that point, contact the maker or a reputable repair service, especially if the computer is under warranty. Tell them what you checked and what you saw, and ask about data recovery if your files were not backed up. The decision between repair or replace is easier once you have a diagnosis and a price.