Thank you for asking this question in the Support Community. There isn't a system diagnostic you can run, but what a lot of people do is ship the units to ADTRAN and have them in warranty repair and return them. The RMA policy can be found on ADTRAN's website: RMA Policy. This way, if the unit is damaged it can be repaired, and if not, you can get a "clean bill of health" for all units.
I hope that makes sense, but please, let me know if you have any questions. I will be happy to help in any way I can.