Who has detailed repair information?
I had to replace the motherboard after the old one failed to turn on completely.
I've learned that the separate laptop components are all required (modem, mezzanine boards for audio and USB, etc) for this laptop to do anything at all – if I don't, the power light comes on and the fan spins, nothing else.
With everything connected (battery, HDD do not make a difference), this is what happens: the Caps Lock light blinks a few times, then flashes rapidly or turns off for a second, and the sequence repeats.
The number of blinks varies, but never matches any of the codes listed here:
The screen backlight never turns on, and there's never any VGA or DisplayPort output either.
Win–V or something else while restarting did something to the laptop. As opposed to 1 blink per second, it now slowly blinks Caps Lock AND Num Lock 5 times total (Num Lock would not blink at all before), about 2 seconds per blink. According to HP (see link above), this means "General system board failure".