I HAVE A SOLUTION (worked for me):
When doing the "Macgyver Hack", I jammed the USB wires into the battery. This pushed the metal spring terminals out. After that, the battery terminal springs don't all touch the connectors in the phone.
Take a needle, and carefully pull the battery's metal springs toward each other.
This worked for me.
Also, try this:
Remove battery and unplug phone. Plug phone in (without battery), then turn on (some phones will turn on without a battery). After the logo comes up, insert the battery. This made my phone recognize the battery and get into the OS.
Once the battery is recognized and you can boot to the OS, root the phone and get the battery calibration app (and use it).
I have a Motorola Defy, and used the Macgyver hack, then had the question mark problem for days before figuring this out.