Would seem things got heated, if one looks at the time stamp sequence, and admin must have clipped the post(s).
To the OP - sorry to hear of your experience, loss and heartache. There are battery isolation switches which can be used to shut off power instantaneously, and as an anti-theft measure too.
I used to use one on my 1800E Volvo coupe.
One example:
http://www.summitracing.com/parts/mor-74103?seid=srese1&gclid=COPtvqLK4rcCFRKZ4Aod5FYA8g
Side or top mount versions are available.
OP- you did everything you could do to save your tractor and fortunately were not injured in the process.
As an EMT you know what's worth saving and lives are it. Possessions can be replaced- people can't. Good luck finding what you want to replace your damaged tractor.
And what caused the fire may never be known, however it may have been something as simple as a rodent chewing on wires.
I bought the house next door from my elderly neighbor. His son insisted the dining room chandelier had some faulty wiring. I immediately removed it from the ceiling. When we went through the house's wiring my electrician found the switch dead because of rodents in the attic having chewed the wiring insulation down to nothing, and a short was the result. Could have been a different outcome for the neighbor or me had we not paid close attention to detail when rewiring most circuits in the house.
My point is things happen, sometimes we can take precautions and prevent bad outcomes, sometimes we can't.