Computer won't turn on: checks before you call a technician
This guide is for anyone who presses the power button and nothing happens, or something happens but not what should. The checks here take a few minutes, need no tools, and in some cases save you the trip to the lab.
What exactly happens when you press the power button?
The answer to this question decides where to look. “Won’t turn on” can be three very different situations:
- No sign of life at all. No light, no fan, no noise. The problem is almost always somewhere along the path of the power: outlet, cable, charger or power supply.
- Lights and fans come on, but the screen is black. The computer does turn on. The problem may be the screen, its cable, the graphics card or the memory.
- The computer turns on, a logo appears, and then it freezes or shows an error. That is no longer a power-on problem but a Windows boot problem. There is a separate guide on a computer that turns on but Windows will not boot.
Decision table: what you see and what to do
| What you see | Likely cause | What to do yourself | When to go to the lab |
|---|---|---|---|
| No sign of life at all (desktop) | Outlet, power strip, cable, switch or power supply | Different outlet, different cable, check the switch on the back | If there is still nothing with a good cable and outlet |
| No sign of life at all (laptop) | Charger, completely drained battery, residual power | Charger light, long charging, power drain | If the charger is fine and there is still nothing |
| Lights and fans, black screen | Screen, cable, graphics card, memory | Input source on the monitor, external monitor | If an external monitor shows a picture (laptop) |
| Beeps on power-on | The board is reporting a hardware fault | Count the beeps and look them up in the board’s manual | Almost always |
| Turns on for a second and shuts off | Power supply, short, overheating | Disconnect external equipment | Yes |
| Liquid spilled on the computer | Short | Do not turn it on | Immediately |
Desktop computer won’t turn on: what do you check first?
Start at the wall and work toward the computer. That way you do not miss the simple thing:
- Check the outlet. Plug a lamp or a phone charger into it. A dead outlet happens more often than you would think.
- Check the power strip. Many power strips have a switch with a light, and some have surge protection that cuts off after a voltage spike. Plug the computer directly into the wall to test.
- Check the cable at both ends. A cable that has slipped half a centimeter out of the back of the computer is enough to cut the current. If your monitor uses an identical power cable, swap them to test.
- Check the switch on the back of the power supply. On the back of the computer, next to the cable socket, there is usually a small switch marked I and O. It needs to be on I. Cleaners, children and cats move it without noticing.
- Do not touch the red voltage switch. Older power supplies have an additional selector switch with the numbers 115 and 230. In Israel the mains voltage is 230 volts. If it is already on 230, leave it there. If you found it on 115, do not turn on the computer. In that position the power supply can be damaged, and a technician should check it first.
- Unplug from the wall for 30 seconds. After a power outage or a surge, the power supply sometimes goes into protection mode and only resets after a full disconnect.
Laptop won’t turn on: what do you check?
A laptop has two power sources, the charger and the battery, and you need to check both:
- Check the charger light. Many chargers have a light on the brick, and most laptops have a charging light next to the socket. No light anywhere? Try a different outlet.
- Leave the computer charging for a long time. A completely drained battery sometimes needs time on the charger before the computer responds to the button at all.
- Check the charger. A phone’s USB-C charger usually does not supply enough power for a laptop. Use the original charger or one that matches its wattage.
- Drain residual power. Even when the computer is off, a small electrical charge remains in the components and can “jam” it. Unplug the charger and any connected equipment, and if the battery is removable, take it out. Hold the power button for about 15 seconds, plug the charger back in and turn it on. That is how HP describes it in its reset guide, and this does not delete any files. Other manufacturers give slightly different times, up to about 30 seconds.
- Look for a reset hole. Some models have a small emergency reset hole on the bottom that you press with a pin. Check your model’s manual to see if it has one.
If the battery is built in, do not try to take the computer apart to remove it. That is a job for the lab, and it can void the warranty.
And what about a MacBook that won’t turn on?
The direction is similar, but the press is different. Apple recommends making sure the cable is firmly connected to a working outlet, then holding the power button for about ten seconds. On a MacBook with Touch ID, that button is the power button. Then press it again normally. If that did not help, disconnect all accessories, including adapters and USB hubs, and try again. If the Mac turns on but shows a flashing question mark or a blank screen, it is turning on, and the problem is in the system startup, not the power. For that we have a MacBook repair page.
Lights and fans come on but there is no picture?
Then the computer is probably working, and the problem is on the way to the picture. A quick test: press Caps Lock. If the key’s light turns on and off, the computer is alive and responding.
On a desktop:
- Make sure the monitor is on and that the right input source is selected (HDMI, DisplayPort). There is a button for that on the monitor itself.
- If the computer has a separate graphics card, the monitor cable needs to be connected to it, usually the lower ports on the back, and not to the motherboard ports above them.
- Try a different cable or a different screen, for example the TV.
On a laptop:
- Connect an external monitor or a TV to the HDMI port. On some laptops you need to press a key combination with Fn to send the picture across.
- Shine your phone’s flashlight on the screen up close. If you can see a very faint picture, the screen’s backlight has stopped working, but the computer itself is fine.
If an external monitor shows a picture and the laptop’s own screen does not, the problem is in the screen or the cable connecting it, not in the computer. For that we have a laptop screen replacement page.
The computer beeps when I turn it on. What does that mean?
The beeps are the motherboard’s way of reporting a hardware fault before there is a picture. Each sequence of beeps is a code, for example a problem with the memory or the graphics card.
There is no single language for all computers. The meaning depends on the board’s manufacturer and its firmware version (BIOS). What to do: count the beeps, note whether they are long or short, and look up the sequence in the motherboard’s or the computer’s manual. Some newer boards have small lights labeled CPU, DRAM, VGA and BOOT instead of beeps. The light that stays on shows where the power-on stopped. On laptops from some manufacturers, a blinking light next to the charging socket or on the keyboard does the same job.
The computer turns on for a second and shuts off right away?
That is a sign the computer is getting power, but something is triggering a protection. Possible causes: a weak or faulty power supply, a short in connected equipment, or overheating. Disconnect all external equipment, including USB, and try again. If it only happens after a few minutes of work, read the guide on a laptop that overheats.
What not to do?
- Do not keep turning on, again and again, a computer that had liquid spilled on it, or that has a burnt smell.
- Do not open a power supply. It has capacitors that hold high voltage even after it is unplugged.
- Do not move the voltage selector to 115.
- Do not use a charger that “looks right” without checking the voltage and wattage.
- Do not take apart a laptop under warranty. The importer’s or manufacturer’s service center comes first.
When to bring the computer to the lab
When the outlet, the cable and the charger are fine and there is still no sign of life. When there are beeps or diagnostic lights pointing at hardware. When the computer turns on and shuts off right away. When liquid was spilled. And when an external monitor shows a picture and the laptop’s screen does not.
With us it starts with a diagnosis, you get a price before any work begins, and we repair only after you approve. Laptops go to the laptop repair page. If the computer holds important files with no copy, tell us in advance. A hardware repair usually does not touch the disk, but it is good for us to know. And next time, a backup before something happens saves you that worry.
Did it not work out?
The goal of this guide is for you to find the problem yourself, and sometimes it really is just a cable or a switch. If you did all the checks and the computer still will not turn on, we will find what burned out or came loose and tell you whether it is worth repairing. You can start from the computer repair page.