There is currently an A600 on Ebay for £12 with a busted key. Takes just a few minutes to work two sad A600s into a new one. If that was my motherboard I wouldn't be struggling with it. Even if the one off Ebay doesn't work you will have gained some valuable bits and pieces. I couldn't rest until I got the 600 back up and running.
Check out the A600 I won for £1 off Ebay. Always fun.
http://www.commodore-amiga-retro.com/amiga/amiga_scuzz93.htmTo be honest if I had more space I would buy those busted Amigas every day of the week. Great fun.