Ok. I think I may have a solution. However, I need someone who basically has just gone only as far as the
bootloader/network unlock to do this bit. After (or before, honestly it probably doesn't matter) this, update
as far as you can. That should bring you to something like version 10.0.16 or so. Point is, need an update further
along than 10.0.13 in order to get back on the t-mobile OTA dole. Do not make any actual modifications to the
system outside of unlocking and doing stock updates.
Perform the `fastboot boot twrp.img` step in the original post. While in the TWRP recovery stage, you would
then perform `adb pull /dev/block/bootdevice/by-name/super super.img`, which will pull a 15gb image off the
phone. this is kind of a super-partition and contains all the system/vendor/etc images inside of it for both slot
a and slot b. With a program called lpunpack you can extract those from it, and hopefully someone stuck in my
and DanDroidOS's situation will be able to use them to flash back to stock.