Can't hardware boot into fastboot.

I think I'm bricked. My shield is stuck in a simple bootloop and should be considered a softbrick. I can't seem to get into fastboot. Forget adb, that's not responding, but I'm still getting the android boot logo. I've tried so many ways. Holding the button, mashing the bettenbetter, plugging at the brick, power at the console, just about everything. Anyone figure out how to get into fastboot with hardware? If so, please let me know or I'll be throwing this out. It just won't seem to respond to fastboot. Such a shame.