Nasty. Looking at the location of the burn, its in the same spot as the damage usually seems to occur- where the cap leads are soldered (there is also a tvs soldered to the pcb in that location too I believe).
The engineers are no doubt familar with this issue; what has become of the once great hvmaxx? Seems the 'updates' to the hardware inside the esc & that cursed new cap unit have caused more problems than they didnt need to solve in the first place (my original hvmaxx system never blew up due to over gearing or a dodgy cap etc). Go and kick the tech guys in the shins will yah NovakTwo....