Hi
First of all: REMOVE THE LEAKING ACCU !!! Just cut it of.
Then you should have a look at the sockets, especially the CPU that lies beneath the battery. You should carefully remove it from the socket, use some contact-oil to clean the contacts (check all other sockets too, some contact-oil will not harm) and press it back in the socket. You may have to wait some time (half an hour) before you power-on the Amiga again (let the oil work). Press all chips in their sockets.
I've required two days to get an old A2000 back to work, at least it was crashing very often until I found out that one of the CIA8520 was bad and the first disk-drive too, so it always crashed at the same game I used for testing at the same time. Now it works :-)
Noster