I was having the same problem as you... see my thread below. 

I had to wash the board 5 different times to get it to work.  I also discovered pin 50 bent, touching pin 49 on the cpu, which was causing an issue.  So look for something similar - maybe in another ic, etc...  Also...  Once I removed C13, the short went away.  This is why I thought it was in the audio circuit.   If I plugged speakers into the headphone jack the short also disappeared.

I then "baked the board" at 190 F for about 15 minutes, and recapped afterwards with new capacitors, once more.  It then started normally.  So try those things, and good luck.  Remember not to give up.  And be sure to completely get all water out of the board.  Baking the board I think is what solved the issue for me.

Edit - if you bake the board - remove everything you can beforehand- battery, roms, battery holder plastic, ram, vram, etc...

bibilit said:

Thanks to everyone for support.

I will have a closer look, and hope to find something.

I have checked with hard drive disconnected, without VRam and Ram.

Click to expand...