"Any update on this issue? 

I'm experiencing the same symptoms - diagonal (opposing) motors get really hot (cant touch them after 5 min flight) while other ones are cold as ice. 

Quad is stable, flies ok (there is some drift but still have to tweak…"

"Having the same problem! Happened just now. I've checked output voltage as Al suggested, mine reads 5.02 V input - 0 V output...  :( 

Contacted jDrones for support.. 

Just wanted to share this info w/ You guys - looks like that voltage regulator…"