PowerBook runs only on ac after dc-in board replacement

Last June, my darling toddler poured a 20 ounce cup of water carefully onto my keyboard, in what we now call the Waterfall Experiment around here. I took the back off immediately, but did not remove the boards inside,and let it dry out on its side for two days. It powered back up, but would not recognize the battery, and no lights on the battery indicator. So bought a new one from a supplier, and put it in, and still no recognition, by Coconut Battery or Hardware Overview. Got a replacement battery from supplier, and Coconut Battery, could see it was fine, but it would not charge or run the computer. I started trouble-shooting, looking for corrosion, but found nothing obvious on any of the boards. Discovered that if I leave the battery indicator circuit cable off, the battery will charge. But then the dc-in board started to spark when I plugged it in. Got a new dc-in, installed it, and the new battery started charging (sans indicator circuit... that still kills it.) But now, with a 100% charged new battery, if I unplug it, the computer dies immediately. It will not boot off the battery either. Reset the SMC a couple of times. Put in my old battery, and it too charges (to 69% of design capacity, according to CB), but will not run the computer.

So it looks like I now have a little desktop with two useless batteries unless:

1) I am missing something that you can think of ? or

2) someone knows where on the logic board this stuff is controlled so that I can try cleaning it.

I don't think replacing the logic board is likely to be cost effective at this point... Thanks for any ideas!