If ever you have a laptop that will not come on, do not assume the motherboard is bad. It may be something connected to the motherboard that is bad. I have had many HP laptops with this problem. But it is possible that it affects other models too.

This problem happened after I just replaced the broken screen, which at my cost was $180. (It is a beautiful screen.) A few weeks later, this HP laptop no longer powered on. The LED light by the power connector – which is integrated into the power connector – never came on. Since this light only comes on when the motherboard works, I naturally assumed the laptop motherboard was defective. The person was using a cheap generic Chinese power adapter and I thought it could have damaged the motherboard.

But, I was wrong. Here is how I eventually figured this out.

I ordered a replacement motherboard using the part number found in HP’s service manual for this laptop. (Thankfully, the service manual was easy to find and included the correct part numbers that I need to order.) Another $150 at my cost. After replacing everything, the laptop still didn’t power on nor did the LED light with the power connector. I next assumed the power connector dongle was bad.

I was wrong again. Using my volt meter I found that the dongle was delivering the correct voltages. So I reconnected the dongle, pushing it in very hard. On this model of laptop, there is a separate USB adapter that connects by a ribbon cable and it sits above the power dongle. I did not connect this because I wanted to make sure I had the power adapter wire pushed in tight enough and with this ribbon cable connected I wouldn’t be able to see that. Therefore, I left it unconnected. I plugged in the laptop power adapter, and the light came on! After removing the power adapter, I reconnected ribbon cable to the USB adapter. No light. It took me about 5 minutes before I finally realized that the light by power dongle wire would never come on when the USB adapter was connected to the motherboard. On the model, the USB adapter also has the power button, so it will have to be replaced for the laptop to work.

If ever you have a laptop that will not power on, try removing all ribbon cables and the battery first. Never remove the CPU fan cable! Connect the power adapter and see if anything lights up. Reconnect one thing at a time – I would start with the display cable – and plug in the power adapter. If the light does not come on, disconnect that one thing and finish with everything else. Now you know what you need to replace. Also, don’t assume it is just one thing that needs replacing. You may replace the motherboard, for instance, and it still doesn’t work because a second part is also defective. It my example, I tried installing the old motherboard again, and the light by the power adapter didn’t come on even with every ribbon cable disconnected.

There is also other generic answer that may work too. If it has a CMOS battery, remove it and and regular battery, remove power adapter, then hold the power button down for one minute. Wait 5 more minutes and put the CMOS battery in, but not the regular battery, and connect the power adapter and try again. If it still does not work, repeat this, except wait overnight. If it still does not work, repeat but wait a week. I have seen HP laptops work again after all power was removed for a month.