Yellow screen is also a sign of poorly seated or missing daughter card on the 3000/4000. (Where all your expansion cards plug in). Pull the daughter card, clean up it's connectors with a large eraser, clean with a bit of alcohol and carefully reseat it. Nice and strait, no funny angles. Also check the receiver slot for any junk, blow out any dust. I've had luck running a very fine finger nail board down the slot to clean contacts. (Don't use one of those cheap coarse ones)
Also if any of the battery leakage got under your memory stick holders, you may have trouble there. If you're not a semi-pro with a soldering iron, I'd suggest finding one if messing with the memory sockets thought. Easy to damage.
Plaz
