Here's a quick guide for restoring the Aria completely back to the factory rom. This is good in case you need to take your phone back for warranty, problems, etc.

1.) Download ATT Original Shipped ROM file from here:
HTC Mobile Phone Support - HTC Aria
2.) Disconnect USB connection to phone.
3.) Power down phone
4.) Boot into Fastboot Menu (hold trackpad on start)
5.) Insert USB
6.) confirm that the phone shows "FASTBOOT USB"
7.) Run downloaded exe file
8.) Process will take a few min at the end you should have a 100% restored and unrooted phone.

[Source: Redapex - XDA]