Spread the legs on the main CPU chip it may not be making a proper conection with the socket. I had a real problem with a bad battery leak and four of the spring socket receivers were cracked. I didn't give up and cleaned both the chip and the socket. I then very gently spread the legs on the chip wider so that it really made a connection. That worked. I have had similar issues with a Gary on an A500Plus and a Denise on an A3000.
https://www.scuzzscink.com/amiga/scuzzblog_february21/scuzzblogdfebruary21_2501.htmWorked for me anyway.
