I just bought a Firepower back in May which had to be brought back to life. One of the reasons I bought mine is the boards had never been touched and there was absolutely no battery corrosion. As some of the other posters had stated, it's a fun game and lots of people like it.
You got the manual and schematics which are a MUST. Check all your fuses to make sure they're the correct amperage. There's a little diagram to the right of the power supply board. Don't forget the two 4 amp slow blo's on the sound boards and the 20 amp in the cabinet for the main. I removed all the boards and cleaned them. I would label the connectors. Especially the driver board. There are 12 not counting the 40 pin, which you'll have to replace, at least, the female side. If the battery holder has any corrosion, remove it and install a backbox mounted remote holder. Clean any corrosion you may find underneath with vinegar or mustard. Wipe off and coat with clear nail polish. Anything burnt, replace. Male or female connector pins. Otherwise clean the male pins. I use 90% alcohol and cheap dollar store qtips. You can also use a fiberglass eraser but nothing harsher. Those lamp resistors gotta go. The cylindrical red things on the driver board. They're toast.
With the boards off, check all the male connector pins. Some probably have cracked solder joints.
That power supply has had some "stuff" done to it. C15 filter cap should be somewhat smaller and mounted to the board under the heat sink and not in the backbox. There should only be one large filter cap in the back box. Not two.
As always, disconnect all outputs from the power supply and check your voltages before connecting the other boards.
Electronic parts. greatplainselectronics.com
Good source of tech info.