I have a iMac G4 1.25mhz. I just swapped out the power supply and battery. Now the computer works (boot chime ok, fan, ok.), but the screen is too dark. There are a lot of different arguments on the forums, most of which are to just connect an external monitor. Other arguments include the backlight being out, and the inverter board being out. I don't even know what an inverter board is. HELP!