my Dell inspiron N5510 i5 displays a white screen when start up. the pc only powers up when power supply is connected. no display on a connected external monitor. i tried 2 different monitors using both a VGA and a HDMI ( the one monitor gives the feedback that no HDMI signal output from the PC). tried to use Power+Fn but does nothing. caps lock button is unresponsive. have cleaned and reseated the components but same problem.

any suggestions on how to fix this? how to narrow down what the cause is? at this point not sure but thinking its a motherboard issue.