If your battery is low or dead then you have several options, two of them "free" and several requiring a purchase.
First, find someone with a Bionic that will let you charge your battery in their phone.
Second, cut a charger cable or USB cable and hot wire the stripped ends to the battery terminals in the phone to charge it enough to recover the phone. This is dangerous and not recommended but it will work and can be managed on your own if you have a spare cable.
Third, buy an spare battery which will likely come with enough charge to get through a flash cycle.
Fourth, buy an external battery charger and use it to charge your battery completely and then restore your phone.
Fifth, buy a Motorola Factory flash cable or make one yourself if your are skilled with a micro soldering iron and motivated. This type of cable has a different pin out and has the +5v on pin 1 which bypasses the battery and powers the device directly even without a battery inserted at all.
This is a permanent solution and such a cable can be used to restore any Motorola device and many others that are configured in the same way.
There is only one place to get one publicly, and I should disclose that I am directly involved with that place. We sell these cables and had them produced for us to our specification just for this purpose.