Don't just jump in an try to do mods. Get practice on electronic kits.
When something was not going right you should have waited. I can gaurantee you that trying to rush an upgrade will result in something broken.
My recent strategy for unknown equipment was to pull everything apart and then reassemble it, without changing anything.
I don't know if they make an agnus upgrade practice kit...
Also, if my memory serves right, I had just broken the A500 with a screwdriver so I knew how delicate those sockets were. When I upgraded the 2000 I made a tool to extract the chip and that was a success, but that A2000 was extremely brittle and faded (like the MB sat open in the sun for years or something) and the stupid thing cracked on install.