As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CLE FLIGHT 2423 - THE CREW REPORTED AN APU FIRE WARNING DURING TAXI WITH APU AUTOSHUT DOWN. THE AIRCRAFT RETURNED TO THE GATE. MAINTENANCE INSPECTED AND REMOVED EXCESSIVE BUILD UP OF ICE AND SNOW FROM THE APU INLET. OPERATIONAL CHECKS OF APU WAS GOOD. THE AIRCRAFT WAS RELEASED FOR SERVICE.