ESC burn out mid flight

[atomiclama]

Had a bit of a burn out on Mondays flight.
First flight went fine, chucking it around the sky and getting used to faster flips.

Second flight as coming out of the flip the thing fell out of the sky, opps.

Checked it over couldn';t find anything wrong so carried on. Same happened again a few minute later.

This time spotted one of the caps on the ESC had come loose. So pulled it off, the thing still flew ok with out it.

But coming out of a loop it fell from the sky again this time with a bit of smoke coming from the ESC.

One of the FETs has burnt out.

So what do people think. brown out of the micro leaving one of the FETs on?

I thought the Caps were for spikes in motor demand not powering the micro on the ESC. 
Think I';m going to have closer look at the circuit on the ESC there should be a bigger cap on the 5V line.