As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
UHLA - BUF/TTN - FLT 127 - DURING PRE-FLIGHT CHECKS, MAINTENANCE CONTROL WAS NOTIFIED THE FORWARD OVERHEAD EMERGENCY LIGHT WOULD NOT ILLUMINATE. MAINTENANCE REPLACED EMERGENCY BATTERY PACK PS2. OPS CHECK GOOD. AIRCRAFT CONTINUED WITHOUT FURTHER INCIDENT. (X)