Safety first
- Computer won't turn on
For desktop and laptop owners with no power or no picture: find the cause, try safe resets, and know when to stop and get it repaired.
Check for danger signs first. Never keep trying to power on a computer that is damaged, hot or wet.
- Any swelling, smoke, burning smell or spilled liquid?
Swelling signs: a laptop case, keyboard or trackpad that bulges or lifts, a gap opening along the seams, or a laptop that rocks on a flat table.
- Swollen battery: go to step 3, Turn it off and unplug the charger
- Smoke or burning smell: go to step 5, Unplug it and move away from it
- Spilled liquid: go to step 7, Shut it down and unplug all power now
- None: go to step 9, No warning signs
- Turn it off and unplug the charger
Don't charge it, press on the bulge, bend it, or try to pry the battery out. A punctured lithium-ion battery can catch fire.
Keep it on a hard surface away from anything that burns.
- Swollen battery. Take it to the maker or an authorized repair shop
Ask the maker about a replacement. Swollen batteries must be shipped and recycled by approved methods, not put in household trash.
- Unplug it and move away from it
If there are flames or heavy smoke, leave and call emergency services. Don't use water on an electrical fire.
- Don't turn it on again. Get it inspected for repair
- Shut it down and unplug all power now
Don't dry it with a heat source or compressed air, and don't put it in rice.
Apple's one-year warranty and the standard AppleCare Protection Plan don't cover liquid damage. AppleCare for Mac with accidental damage cover may.
- Liquid damage. Get it checked before you turn it on
- No warning signs
Power
- Check the outlet, cable and power strip
Plug a lamp into the outlet to test it. Plug the computer straight into the wall, not a power strip or surge protector. Reseat the cable at both ends.
Desktops: check the switch on the back of the power supply is on.
- Is it a laptop?
- Charge it for at least 15 minutes, or longer if the maker says so
Check the charger's light. If it's off or blinking, try another outlet or a compatible charger.
Then go to step 15, Do a hard reset
- Desktop is on a working outlet
- Do a hard reset
Unplug power and every accessory: USB drives, printers, docks, memory cards. Take out a removable laptop battery.
Hold the power button for 15 to 20 seconds, then reconnect power and turn it on. This doesn't delete files. Sealed-battery laptops have their own reset steps on the maker's site.
- Any sign of power now?
- No power. Book a repair with the maker or a repair shop
The power supply, charger or main board may have failed. Note the model, serial number and what you tried.
- Count the beeps or flashes
The pattern is a hardware error code. An amber or orange power light can also be one.
- Look up the pattern on the maker's support site
Search your model and the pattern on the Dell, HP, Lenovo or Apple site. Common causes are memory, storage or a board fault.
Don't open the case unless the maker's guide says that part is user-replaceable.
- Hardware fault. Book a repair and quote the code
- Check the display and its connections
Desktops: the monitor must have power and be on, with the cable in the right port and the right input source selected.
Laptops: turn the brightness up, and connect an external monitor to test the built-in screen.
- Try the Windows wake-up keys
Press Windows + Ctrl + Shift + B to restart the graphics driver. You may hear a beep or see a flicker.
Press Windows + P, then P again and Enter, to cycle display modes. Mac users skip this step.
- Is there a picture now?
- Computer starts and shows a picture
- Does an external monitor show a picture?
- Built-in screen or cable fault. Book a screen repair
- No video signal. Book a repair with the maker
- Startup problem
Startup
- Which system won't finish starting?
- Windows: go to step 31, Force Windows into Recovery mode
- Mac: go to step 33, Start up from macOS Recovery
- Force Windows into Recovery mode
As Windows starts, hold the power button for 10 seconds to force it off. Repeat 2 to 3 times until Recovery mode opens.
- Start in Safe Mode
Choose Troubleshoot > Advanced options > Startup Settings > Restart. Press 4 or F4 for Safe Mode, or 5 or F5 for Safe Mode with Networking.
In Safe Mode, undo the last change. In Device Manager, roll back a driver that was just updated.
Then go to step 35, Does it start normally now?
- Start up from macOS Recovery
Apple silicon: hold the power button until "Loading startup options" appears, then click Options > Continue. Intel: press the power button, then immediately hold Command-R.
- Repair the startup disk with Disk Utility
From Recovery you can also reinstall macOS or restore from a Time Machine backup.
- Does it start normally now?
- Startup is still failing. Save your files and book a repair
If you can reach Safe Mode or Recovery, copy important files to an external drive first. A repair shop can often recover data from a drive.