You say you verified the fuses were good, but did you verify they are the correct values? I was messing with a Hollywood Heat for someone and instead of blowing fuses it fried some stuff on the Driver board. Once I replaced fuses with the right values, then it helped to track down what the real issue was based on the fuse that kept blowing. (ended up being one of those drop target reset little coils on each target - no idea if Genesis has those)

It had a weird issue with the feature lights cutting in and out during gameplay... that ended up being just a bad solder joint where they all tied in under the playfield. So the first light was working, but the rest weren't when they cut out intermittently. At first glance it even looked okay to me, but a second set of eyes noticed the crack in the solder.

System 80b games are an adventure for sure, good luck, eventually you will figure it out.