I think diagnosis pending is their catch all term for this recall... if you tracked the FedEx package back to them, and it has arrived, essentially, you're just waiting for them to package and send back another one - and they'll send you a notice when it ships.
Funny with ours, we got the email notification that it had shipped on the actual day it arrived! I'm sure it's been mentioned before here - you must sign for this package, they won't leave it on the doorstep.