As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING TAXI IN, NR 2 ENG SHUTDOWN. PUT THE APU GEN BUS TO ON AND LOST POWER ON BOTH BUSES. AFTER APU GEN BUS DISCONNECTED POWER, TRIED TO PUT THE NR 1 ENGINE. GENERATOR BACK ON LINE AND IT WOULDN'T CONNECT TO THE BUS. ACFT GROUNDED. REPLACED APU BREAKER C803, INSTALLATION TEST GOOD IAW MM 24-21-41. RAN ENGINES / APU AND TRANSFERRED POWER BETWEEN SOURCES SEVERAL TIMES, OPS NORMAL.