As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING TAXI IN, APU WOULD NOT START AFTER 3 ATTEMPTS EICAS MESSAGE FOR APU FAULT WAS PRESENT. PERFORMED APU ECU BITE TEST ECU BITE SHOWED APU INLET DOOR START ONE ABORTED START 2 AND 3 FOUND DEICING FLUID IN APU INLET DOOR CLEANED S506 INLET DOOR OPEN SW STARTED APU 49-11-00 OPS CKS GOOD SEVERAL TIMES</P>)