Have you had any luck, since I borked my device last night I too am currently stuck at xaa/xaa/vzw and cannot get it to reset.
@GDHAMTON7 I was able to fix my csc by using the DUE1 firmware for both carrier version and U1. I flashed the carrier version first complete with the CSC file, not home. Booted and didn't have any luck with it resetting to vzw/vzw/vzw. I then flashed just the CSC file of the U1 firmware and factory reset. Upon going through setup and then inserting my sim I did get the popup of device needing to reboot to apply carrier config. Since I was wanting to be on U1 firmware I then flashed the DUE1 U1 firmware with the home CSC file and factory reset and all is well.
If you are still stuck with xaa/xaa/vzw, I hope that this may help you as well.