I don't think it's the heat exposure. Most components can run up to 85C or 125C (that's 185F to 257F)... I wouldn't think you were working in that kind of environment.
anyone knows if swapping the polarity would whack it? Maybe, maybe not. Depends on the circuitry inside. Probably not.
was running quite hot earlier in the day which seemed odd since it hadn't been running hot during earlier uses of it This is a clue. My guess is just component failure. Possibly in the power section.
(Just to be funny, I would blame Rohs
. Gear is much more reliable in the old days when we're allowed to use Pb-Lead. On the bright side, when you chuck your dead unit into the landfill, it will be at least environmentally friendly, and you can buy a new one to toss again in the landfill later on.)
P.S: There's a reason why Military Gear, aerospace, medical life support, implanted devices, are exempted from this Pb-Lead ban. Care to guess?