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Computer won’t turn on: what to check, in order

By Editorial Team Published 2 min read
os general tested 2026-09-09 retest 2027-03 by editorial team
Quick Fix
01 Plug the computer directly into a wall outlet you know works — bypass every power strip, extension and surge protector.
02 Then do a power drain: unplug it, hold the power button for 30 seconds, plug back in and try. This clears the most common no-power state.
tested general · 2026-09-09

“Won’t turn on” covers a few different situations, and telling them apart is half the fix. Note which one you have: no lights or sound at all, lights/fans but no screen, or powers on then immediately off. Then work the checklist.

No lights, no fans, nothing

This is a power-delivery problem. In order:

  • Confirm the cable is firmly seated at both ends — wall and computer.
  • Test a known-good wall outlet directly, skipping strips and extensions (and check the strip’s own switch/reset).
  • Laptop: is the charger’s light on? Try charging with the screen closed for 30 minutes in case the battery is flat, then power on. A dead charger or frayed cable is a frequent, cheap-to-fix cause.
  • Desktop: check the rocker switch on the power supply at the back is set to “on” (I), and that the voltage selector (if present) is correct.
  • Do the power drain in the quick fix — remove the laptop battery too if it’s removable.

Lights and fans, but the screen stays black

The computer has power but isn’t displaying. Try:

  • Disconnect everything except power — external drives, hubs, second monitors, USB devices. A faulty peripheral can block startup. Add them back one at a time.
  • Desktop: check the monitor is on the right input and its own cable is seated; try the display cable in a different port.
  • Listen/look for beep codes or blinking LEDs — many machines signal RAM or GPU faults this way, and the pattern tells the maker’s support exactly what’s wrong.
  • Reseating the RAM (desktops, and laptops with an access panel) fixes a surprising number of “power but no display” cases.

Powers on, then straight back off

This usually points to overheating (see our loud-fan guide) or a power-supply fault under load. Make sure vents are clear; on a desktop, a failing PSU is a common cause and a straightforward part to replace once confirmed.

Safety and when to stop

Always switch off and unplug before opening a case. If you see or smell sparks, scorching, warped plastic or hear crackling, stop and get a professional — that’s not a DIY situation. And don’t buy replacement parts on a guess: confirm exactly which component is dead (via beep codes, a known-good spare, or a shop’s diagnosis) before spending, especially if the machine is still under warranty.

Frequently asked questions

What is a “power drain” and why does it help?

Holding the power button with the machine unplugged discharges residual power in the board, clearing a stuck state that can prevent startup. It’s safe and often works on its own.

My laptop shows a light but won’t start — battery or charger?

Try a different compatible charger if you can borrow one. If it starts on the borrowed charger, yours has failed. If not, and the battery is removable, try starting on mains power with the battery out.

Is it worth repairing?

A charger, PSU or RAM is cheap and worth it. A dead motherboard on an older machine often isn’t — price the repair against a replacement with more support life left.

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