Did I brick my phone?
I just upgraded Liberty to 3 v2 through the rom toolbox app. Now my phone won't boot. It just shows the liberty bell motorola logo for a second or two, then goes blank. It just keeps doing that in a loop. Is there any way to fix this, or is it hopeless?
You softbricked it, but no worries, this will get you back up: http://www.droidforums.net/forum/droid-x-rooted-help/100038-complete-droid-x-sbf-flashing-guide.html
flash the Gingerbread SBF file from here: https://sites.google.com/site/motosbf/droid-x-sbf-files
The reason you got the bootloop is you probably flashed the ROM over the wrong kernel version, so make sure to use 4.5.602 or 4.5.605 to flash this ROM (unless you were on 4.5.621 before, if that's the case then 4.5.621 is the only one you can flash).