Have you done the simplest thing to the original computer yet which is to replace the cmos battery?
Yes, as I mentioned I have replaced the battery, and tested the power supply. Both are good. But it will not boot up in the Arcade Legends cab, or on my work table with monitor and ps2 keyboard hooked up to it. Can't even get into BIOS. A new hard drive is $150 and I don't even know if that is the issue. Could be the ram, the motherboard, etc. I just feel like at this point I should just spend the money on an old PC and a J-Pac i(f the J-Pac is even needed).
The plan at this point is to replace the AL computer with a new (old) PC and upload games to it and use the same control panel, cab, and monitor currently used for the AL. To do this I will buy a PC, hook it up in the same way the Arcade Legends computer is hooked up, power it on and hope for the best. If it doesn't work, I will probably need a J-Pac board and then I should be good to go, correct? Thanks again for all of the help, fellas!