A: No. The lock is server-side and checks the IMEI. Even with a custom ROM, the phone still sends the IMEI to Xiaomi’s servers during setup.
A: The finance company may have not sent the release command. Call them. Also, some systems require two full business days to process. the lock remains.
A: No. The lock lives in the phone’s secure partition. Hard reset only wipes user data; the lock remains. the lock remains.