Try the usual. Be sure no USB things are plugged in and do a safe generic reset. In short it's where we power down, remove the battery, press and hold the power button for 1 full minute, release, slip in the battery and test again.

If that fails, go ahead and replace the CMOS battery as it's the cheapest thing that could do this. I no long test this cheap part. It's just replaced since in bulk it's 25 to 39 cents. Repeat that reset again.

After that we have to make the machine smaller as best we can. One stick of ram, no ODD, no HDD and reset then try again. If still dead try without the WiFi card and again test.

If that doesn't change the screen or let you in the BIOS it's something motherboard related. Get repair estimates.