As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED: MULTIPLE ISSUES LEFT PACK FIRST GOT PACK MODE LEFT FOLLOWED BY LEFT PACK. PERFORMED CHECKLIST RESET GOT PACK LEFT BACK ON BUT SOON PACK MODE LEFT AGAIN. SMELL OF SULFUR ON TAKE OFF AND WHEN PACK WAS REINSTATED. SULFUR SMELL LAST 3 TAKE OFFS. REMOVED AND REPLACED FORWARD ELECTRICAL AND ELECTRONIC COOLING FAN PER DMC B787A-21-27-12-00A-720-A-A.