KABOOMER!

I have an Ultra Pong Atari, which does not turn on, I do not have the original adapter but I have tried it with a generic one and with batteries and it seems that there is no current flow, since there is no sound coming out of the speaker, as I got it from The second hand had traces of empty battery liquid and some varnish that covers the circuits was descaled on the plate, everything else seems fine, I already cleaned everything with isoprpilic alcohol, I checked welds but still there is no sign of anything, any suggestions to replace some of the circuits or maintenance manual to check for possible failures? Thanks in advance.