PROBLEM WITH ACER ASPIRE 1520 LAPTOP

[TFLOOKLAP]

Have a laptop from hell here,it has worked well for just over three years.Was playing Far Cry on it two weeks ago,whem the laptop froze up.switched it off/back on -no display-nothing.Since then have tried another video board-as got error beep code on swtich on- 1 long and two short-this was reported in manual as video checksum error.Have tried another motherboard-was doing nothing-with original video board-other video board sent back as believed problem was not that.Have tried the crisis recovery disk method,made one up with latest bios-loaded using bootblock dipswitch operation.The wierd thing is this video graphic is nvidia but when this crisis disk is loaded.laptop powers up and just sits there-it does nothing else.But when i load the uma video crisis disk,the laptop comes up-in that hdd light comes up, wireless led comes up,keyboard registers caps lock/num lock/hibernate keypresses and beeps if memory/keyboard removed-but no video-nothing-nada.
So my question is what is the faulty item.And why is the uma crisis build the only one i get life from this laptop-the nvidia crisis disk does nothing.
Any suggestions?

[edwin]

so, no matter what board or video card you use you get no display. possibly the inverter or the screen itself gone?

[TFLOOKLAP]

Have tried a repl video board (2nd user)- with original motherboard,and a motherboard (2nd user) with orig video board.but with both initially did nothing-ran crisis recovery disk-nvidia one causes no error beep-no operation,and umb crisis recovery causes error beep,and indications of some correct system operation concerning keyboards/leds-also beeps without memory/keyboard-but no video from either.

[TFLOOKLAP]

have removed screen connector with repl 2nd user motherboard-orig video card.no video from secondary vga output-with nvidia image