HP 840G2 only usable by holding down the power button

[jss127]

A few days ago I started having problems booting up my laptop.  Shortly after i get to the screen where I enter my password on bootup the computer shuts down.  After lots of trial and error (including removing the battery) I realized that constantly holding the power button down the computer works perfectly!  

I've MacGyvered a workaround using a clamp to hold the power button down but obviously that's not a great long term solution 😞  Does anyone have ideas what's going on?  The other strange thing is that when I hold down f2 to get to the diagnostic screen the system works fine without the power button held down.

Thanks for your help!

[WAWood]

@jss127 

My guess is that your circuit leads underneath the power button have deformed over time.  This can result in lack of reliable contact, forcing you to hold down the button, but it can also lead to intermittent shorts -- even when you are not pressing the button.

When you are in Windows, that circuit is constantly being monitored and if there is a sudden short, Windows will power off the PC, thinking you pressed the button.

But the BIOS does not do that monitoring, so there, you would have to press the button yourself to power off the PC.

To check this out will be expensive because intermittent faults can not be reliably checked and your only recourse is likely to be having the power button and contacts replaced and that will require disassembling the laptop -- not something you should attempt.

[jss127]

Thanks again for your insight. Is there any way to stop Windows from checking the power button?  The laptop works perfectly with the clamp in place. Hate to spend money on this older laptop.

Thanks!