As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PILOT REPORTED AFTER T/O THRUST WENT TO T/O RESERVE AND IT COULD NOT BE CHANGED TO ANY OTHER SETTING. A/C PERFORMED SAFE RETURN BACK TO EWR. MX REMOVED AND REPLACED THRUST RATING MODULE PUSH BUTTONS AND PERFORMED OPERATIONAL CHECK GOOD. A/C WAS APPROVED FOR RETURN TO SERVICE.