board dead now shorts where there shouldn't be!

[lewisss]

Hi, I hope someone can help, I built my mod a week ago and everything was working perfectly, i have run all the production tests, battery analyser, and case analyser. 

everything was working perfectly until just now!

I had the unit hooked up to escribe and it was great then as i took it off of the` mini usb i heard a 'pop'
and the screen went blank.on inspection the fuse had blown.

fortunately i ordered a spare fuse just in case when i ordered the board but before .replacing it i took the board off and visually inspected it to make sure there were no obvious signs of metal contactin metal where it shouldnt. i couldn't see any so replaced the fuse (not straight but good contact)


plugged in the battery and 'pop' again fuse 2 down the drain!

So did some continuity testing 

B- to B+  = open as expected
B+ to bottom of blown fuse = short as expected
B- to top of blown fuse =short not expected 
therefore when the fuse is intact the battery terminals are effectively shorted.


I needn't have gone on but here are some other readings for information

B- to three ground = short as expected
B- to ground 501 output =short as expected
B- to +ve 501 output = Short, not expected
i cut off the 501 connector to check that was not a problem and it wasn't

B- is also shorted to outboard switch pins No 2,3,6  expected
and the three mounting hole pads. also expected

the 4 conections for the balance port have no shorts between themselves, nor B+ and B-


any ideas, or is the board shot?

if so what do i do next?

[xevape]

I had this issue on one of my boards which blew out my USB bus on my PC...If you were to plug it in did it effect your USB Bus or just blow the fuses?