Autofire DNA200

[Everest]

I made a post in the 'connectors, components and accessories' foum, but after doing some searching I found some threads using the keyword 'autofire' in this forum and thought I'd x-post here (hopefully a moderator can delete my thread in the other forum).  

I was sitting at my desk today, and suddenly my RDA erupted into flames.  I yanked the side cover off my enclosure and pulled out the battery (a 3S 1300mAh lipo pack) and found it to be cool - I still chucked it out on the porch to be safe.  Disassembling the device, no components seem to have fried, the fuse is intact.  Checked function of the 'fire' button and it is correctly open/closed like a switch should.  Then I checked continuity between the battery connector and the 510 connector - low and behold there is no resistance between negative battery / negative 510 and positive battery / positive 510.  I de-soldered all the connections (board to 510, battery connectors) to check the naked board - and sure enough there is continuity between the battery +/- straight through the device to the output pads.  

 

According to some other threads, autofire can be caused by a connection between the via at the edge of the board and the output pad to the 510 connector.  I cleaned up my pad with some de-soldering braid, and lo and behold they are solidly connected.  

 

The mod has been in service for ~8 months - what would cause these two to short?  That solder pad shouldnt be getting that hot or anything.  I'm thinking I need to cut the trace / use an exacto to separate the connection between those two pads.  Anybody have any thoughts/tips for me?