Here is the suggestion:
1. As for the Serial Number Unknown problem, please try doing a factory reset. If it does not work the first time, after the reboot, please try it again and once at the desktop, wait about 10~15 minutes for the system to sync with the server. So far this has worked for users I am directly assisting at the moment on another forum but it has not worked on two particular units that were returned yesterday.
Might be an idea for users with this issue to give feedback in a separate thread here.
My Result: I've tried it twice, unit still reports an unknown serial number.
To be clear the prime has never been rooted or attempted to be rooted and was factory plastic sealed when I got it.
I have not been able to download any OTA updates, but was able to manually update to Honeycomb .33 from Asus support site.