As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
INSTALLED 'OVERHAULED' REVERSE CURRENT CIRCUIT BREAKER ON AIRCRAFT. PLACED BATTERY SWITCH AND MASTER TO 'ON'. BATTERY WOULD NOT COME ON LINE. TROUBLESHOT SYSTEM AND FOUND AN 'OPEN' BETWEEN THE 'GENERATOR FIELD SWITCH TERMINALS'; THUS, NOT ALLOWING THE BATTERY RELAY TO BE ENERGIZED.