I try to avoid comments about specific sellers after taking some heat from "a rude guy in Canada" however I did buy one of those untested A3000 motherboards on ebay you are probably looking at.
It is complete junk, infact you can have mine for the price of packing and shipping if you really want it, I don't:-). It is an early revision unfinished board with TONS of solder work already done, ports missing and damaged, chips missing, ect. To top it off it looks like it was sitting in a stack of 50 or so and then someone played frisby with it.
A3000's are wonderful machines. Don't give up on yours. Either buy one from a trusted person on here, or just hold out for a nice complete one on ebay and interview the seller first asking for extra pictures and information. If it's the one you want just out bid everyone and sit on the extra parts. They usually sell for less than $200.00 Be patient:-D.
Good Luck
Jeff
As for the residue from the alcohol on your board it shouldn't hurt anything. Just get some electronics cleaner, a soft brush, and some compressed air. It should look like new again.
