If maintenance procedures for testing did not correctly specify that a retest must start, then restart the system to actually test that the repair was successful, then that replacement may have been tested while the computer was being fed data by the correctly operating sensor. They would have had to attempted a single boot between flights for the next flight to have flown with the untested replacement sensor. If they didn't test at all, then it's possible both sensors had a problem.

This is of course assuming that there is any retest procedure at all in the documentation given that the AoA sensor wasn't classified as safety-critical.

It really seems like the makings of a bad movie doesn't it?