If you have low battery then you have several choices.
First, buy a spare battery or an external charger.
Second, borrow someone's Bionic to charge your battery in.
Third, hotwire a charger to your battery buy cutting off the ends and physically connecting the wires to the battery contacts. This is NOT recommended for obvious reasons, but it does work and you can even find video tutorials on YouTube to help you with it.
Fourth, use a special USB cable known as a "factory cable" which has a different pin out than a normal USB cable that will power the device directly, bypassing the charging circuit, with the battery removed.
Where do you get one?
Well, you can make it yourself if you are very handy with a soldering iron and have a good workbench setup with a micro tip soldering iron and station setup with jigs etc. to hold everything in place, or you can buy one from TBH.
We got a few of these cables from our sources at Moto a while back and realized how valuable they were for users wh flash their phones often and are likely to end up in this situation.
So we went to the trouble of figuring out what the pin out arrangement was by dissecting the cable and had a small number produced for us by a local supplier.
As a result of this extremely limited production, they are very expensive, but we have them available on our site for $35 if you are interested. We are not in the business of selling cables to make a profit, we did this as a service for our users because we felt it was an opportunity to provide a unique tool that is very valuable that is not available to end users normally.
We are NOT trying to take advantage of users who are stuck with bricked devices and recommend to everyone to always charge your phone completely every time you start any operation which could leave the phone unbootable for any reason and to have spare batteries or external charger in order to avoid the problem, but we do have a permanent solution for you.
Anyone interested can check it out at http://shop.teamblackhat.info/main.SC
We recently ordered a new batch as we sold out and they should be ready to ship in a couple days.