As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING POWER TRANSFER FROM GPU TO APU, MCP ALTITUDE WINDOW LOCKED UP AT 50,000. GROUNDED - YES. VERIFIED FAULT, REMOVED GPU USED ONLY APU NO HELP. USING APU PWR CYCLED 9C/B'S FOR MCP & 4 C/B'S FOR FMC'S. ACCOMP. DFCS BITE GRP TEST 70 FOR MCP ALL TEST PASS & LRU REPLACEMENT TEST PASS. REF. M/M 22-11-34-740-801 & FIM 22-11-TASK 803 VERIFIED BOTH FMC'S PASS SENSOR TEST, TEST OK REF. M/M 34-61-00-710-026.