Ah, there is a fuse on the pack. Pull the fuse. Do they have to remove the 12 volt battery from a car every time someone does body work? I think not. I'm sure that the Official Insight shop manual is available on CD to any dealer if they don't already have it! As for welding aluminum; Aston Martins and aeroplanes are also aluminum bodies. MIG welders are not that rare, you just need someone with experience using it on aluminum.