As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED: AN EMERGENCY WAS DECLARED DUE TO: DURING INITIAL CLIMB OUT WHEN GIVEN A HIGHER ALTITUDE, MCP ALTITUDE WINDOW STOPPED AT 4100 AND WOULD NOT ALLOW ANY FURTHER ADJUSTMENTS. AIRCRAFT AIR INTERRUPTED BACK TO AND LANDED SAFELY AT IAH. REMOVED AND REPLACED MODE CONTROL PANEL, PER AMM 22-11-34-00-801 AND PERFORMED BITE TEST, PER 22-11-00-810-801. ALL TEST PASSED AT THIS TIME NO DEFECTS NOTED AT THIS TIME.