BB Curve 8300 :: SW Update BRICKED In 8310

I'm new to these forums, and to the BlackBerry, having had my 8310 for only a few months (through my company). My daughter, however, has had her 8310 Curve since last March, and she has had intermittent problems with it. She has had to have it replaced under warranty by AT&T twice. This last time, she discovered that her sounds had ceased her alarm did nothing when it went off. The sounds later returned mysteriously, but she decided that that was the last straw. She wanted to take it back to the AT&T warranty center to get it replaced again, but I suggested she attempt to upgrade her system first. My theory was, since the new software was released, it would make sense to upgrade. My company phone has been upgraded (OTA) with no problems, so I thought (silly me) it would be just as easy to do my daughter's Curve.

The first thing I did was go to her Options/Advanced Options screen to do a wireless upgrade. However, that option was not available on that screen. Odd, I thought her phone and mine are identical, and mine had the wireless upgrade option. So I came to these forums and looked for some assistance, and found the sticky at the top of the forum about the 4.5 software upgrade. I followed the link to the BlackBerry page that contained the download for the AT&T software (making sure I selected the AT&T multilanguage version of 4.5.0.182). I downloaded that version, but decided before launching it to use BlackBerry Desktop Manager instead. It dutifully reported that her Curve needed a software upgrade to 4.5.0.182, so I decided to attempt the upgrade over the USB connection. When it got to the point where it had backed up her phone and was ready to do the system backup prior to wiping it, the connection broke. Don't know why - I used the BB-supplied USB cable. So, the upgrade didn't happen that way. The next thing I did was launch the AT&T download that I had retrieved from the BB link. It dutifully installed the latest BB Desktop Manager (5.0.1, I think), then when I hooked her Curve up to the computer it once again reported that she needed a software upgrade. I elected to do the upgrade, and it went through the process again, backing up the Curve to my computer and getting ready to wipe. This time, it again broke the connection, but when I chose "Retry" it seemed to proceed as normal, erasing the device in preparation for upgrading. Now the fun begins. When the actual upgrade began, the device broke the connection again. I once again got the dialog box with the "Retry" and "Cancel" boxes, and clicked "Retry." But when I did that, the screen on the Curve went white and revealed an icon which I can only assume means, "No OS installed," along with the small number "507" underneath. The BB Desktop Manager appeared to be attempting to upgrade the software, but after leaving it setting like that all night there was no change in the status. So it is well and truly bricked.

My question now is, what is my recourse? Is there any possible way to recover this device (since the computer does not recognize it through the USB connection)? Do I simply need to take it back to AT&T and have them replace it (again)? And will the backup I did last night be restorable to the new BB (assuming they give her another Curve)? I hope to get some answers fairly quickly, because I'll be able to hear the eruption from here when she discovers her Curve is a paperweight. Thanks in advance for your help, and your availability for BlackBerry users.

SW ver 4.5.0.182 (platform 2.70.106)