The front panel counter you describe as "AP" is actually (due to the limited LCD display) "RP" - it's checking the return path, trying to verify it has two-way communication - I.e. that it can send a signal back to the cable company.
The counter will get to 53 if it sees suitable conditions, or give up at 52 if not.
The counter will get to 53 if it sees suitable conditions, or give up at 52 if not.