Ok, got the V3 and thought I would just grab the spheroid off my v2.5, grab a new bat and check it out. Whoops, needed the longer Gpin, which too all of about a minute to change. Looking good. Uh oh no fire and button instantly hot. Quickly removed the top cap/spheroid and yup bat is hot. Set it aside and inspected the bat and switch. Bat looks new and switch looks perfect. Ok, new bat and another try. Nope, same problem. Yikes..
Well, I'm kind of busy right now so putting the spheroid back on the v2.5 and will try to figure this out later this evening. Can't be too hard to figure out, I hope. Any and all wisdom greatly appreciated..
Check the 'seating' of the GPin around the delrin.