Definitely looks like some battery juice crusties on the battery holder. Clip it off and clean up the surrounding area. Doesn't look like it has spread too much which is good. Lots of times it works its way down to the PIAs on the driver board which are directly underneath. Recapping the power supply is easy if you are decent with the soldering iron. The 40-pin is kind of a pain if you don't have a good desoldering solution. Also be sure to check the sockets on the CPU as outlined in the guides.
I just picked up a project Firepower myself but the CPU and driver are both pretty hosed with corrosion so I have to replace a whole ton of stuff. I predict you will be up and running after doing PSU/40-pin/sockets.