As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT GROUNDED. SOURCE OFF LT ON #1 GEN @ FL 380. RAN QRH - GEN WOULD NOT RESET. DIVERTED ON APU GEN ONLY. #2 GEN ON DEFFERRAL. CREW DECLARED EMERGENCY. REMOVED AND REPLACED #1 GCB (C801) PER AMM B737-800 AMM 24-21-41. OPERATIONAL CHECKS GOOD.