As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WE HAD AN ATC DELAY WHILE HOLDING SHORT OF THE RUNWAY. WE NOTICED A STRONG ELECTRICAL BURNING SMELL AND A MOMENT LATER WE HAD A REMOTE CIRCUIT BREAKER TRIP "FLAP ACE 1 AC PWR" AND WE RETURNED TO THE HANGER. THE SFACE WAS REMOVED AND HAD VISIBLE BURNS ON THE OUTSIDE OF THE METAL CASING