@cristodcgomez sorry I was unclear: I have also tried selecting "restart" from the bootloader screen as per your hint above, and that also didn't result in the phone being recognized by ADB.
My extra attempt was to go through the recovery menu, which just locks the device when I select the fastboot option.
At this point I feel like something went wrong in the UT install that has messed up my phone's ability to access fastboot.