I have the 2ndbootin thing, the stock moto recovery, and never ending boot animation. If I wipe the cache using the moto recovery, I can get it past the boot loop and then it gets stuck in "android is upgrading". I figured I can flash a custom recovery using RSD, the problem is I don't know, and googling the problem didn't came up with useful solutions. My top priority is to get the phone working again, and that it will have the data is got now (though I did a backup of the data before starting this failed upgrade).
Also relevant:
http://forum.xda-developers.com/showthread.php?p=48088388#post48088388
Also relevant:
http://forum.xda-developers.com/showthread.php?p=48088388#post48088388