Hi Congzilla

The battery has nothing to do with the board problems, except in the case you use one with different voltage, say 7 cells 8.4V. I assume that's not your case.
Maybe your gearboxes are too tight and specially the left one. This stresses the whole transmission causing an overcharge and thus overheating the ESC. If your gearboxes are metal, then do a search in the forum for "running-in" and when you have replaced your board do a careful running-in.
Hope it helps

Regards