mmm up in smoke

i have had a mamba monster for about 6-7 months now i only have 1 setup run
on it (about 5 mins) it has been sitting on my shelf sins then becuase i
live in canada and the weather got to damp for my liking. i run 2x 8000mah
28c smc lipos with it and today i went to swap out my spektrum RX for a
telemetry RX after changing the rx i pluged in the castle link to check for
updates and updated the firmware to 1.22 after that i went to plug my batts
in and bind my RX and the esc went up in smoke and melted the the black wire
off the esc.

why did this happen i havent changed anything in the 2200kv combo sins the
setup run and now iam out of an esc?