My acer aspire 2930 will power on but no screen

This could be a defective backlight caused by damaged CCF's (cold cathode flourescent lights, or a bad high voltage invertor in the laptop.

IF YOUR unit has a VGA connector, connect an external monitor and see if the machine is working. ALSO try hitting F8 repeatedly to see if you can get into SAFE MODE and it might display.

Try to determine if the machine is running and it is just a dead display.

Put a CD in and see if it flashes the activity light showing it is trying to read the directory from the CD.