I had an similar battery issue when I owned a Motorola Defy and I used a tutorial I found on [http://forum.xda-developers.com/showthread.php?t=892026|XDA Developers] to charge my battery. I would expect similar results to help charge your battery. If the bootloop is a result of the battery being low, then this may help, but if the bootloop problem remains, there may be something else going on.
Hopefully, this does work for the battery.