Great news! I was doing some bend testing to see what area I needed to resolder, when I brush the J4 connector and the screen flickers on! So I resolder the J4 connector pins and viola! It works! That little bastard was hiding in plain sight!

On another note, while peeking around inside, I noticed that the motherboard had a daughterboard installed on top of it. This must explain why my 512k is able to recognize the HD20 that came with it! I don't know what kind of voodoo magic is going on with that expansion board, but it somehow turned the computer into a 1024k 512ke! Super wierd because normally M0001w's aren't compatible with HD20s...