The only way would be to purchase a schematic if someone has published one -- but that's generally a $20-30 minimum commitment on a system that's unlikely to be repairable even if you can pinpoint where the fault is.  
Hello All, I have an Inspiron 5555 which won't turn on. I've confined the power adapter DC Jack port works, but beyond this I can't tell if the board is dead. I tried the trick where you use a thin piece of metal to turn on the laptop in place of the button, and set the BIOS to power on when sensing the adapter. Yet nothing works. I'm not sure if this 'trick' can work on the 5555 though I've seen videos of people doing so.  I want to confirm the board is dead before deciding what to do next. I could purchase another button and just see if it makes any difference. Is there a place to test on the board to confirm it's dead. If the power button cable port is shot for some reason it effectively means a dead board since I can't replace it.  Are there also other means of bypassing the button to access BIOS? Thanks!
Diagnosing No Power. Adapter and Port Fine.