I guess the biggest issue was the keys. Verizon techs updated something and now it works again. Going into EPST, the biggest changes were under security (both password fields now have garbled characters), and the HA/AAA Shared secret (same, garbled characters). Having learned my lesson, I've taken a full backup of the service configuration using QPST and am following the instructions
here (both methods) for backing up my keys. Is there anything else anyone recommends backing up before I attempt another ROM flash?