As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SHIP 3043 - ATB - DUE TO A THUMPING NOISE HEARD AT THE NOSE OF THE AIRCRAFT AFTER LIFTOFF. CORRECTIVE ACTION: EXTERNAL POWER CONNECTION ACCESS DOOR WAS FOUND OPEN. COMPLIED WITH SECTION I OF ER/A 633751-14, EXTERNAL POWER TAPED CLOSED AND LABELED AND PLACED ON MONITOR. LATER REPLACED DOOR PLATE/SEAL PER A321 AMM 52-42. (LP 8367922 - AIRCRAFT WAS GROUNDED)