Did you measure the output from the power booster?
Does the booster work by itself, or does it only heat up when you hook it up to the teensy?
If it only heats up when you hook it up to the teensy, I would very much suspect that you've hooked up the booster backwards to the
teensy. (It should be hooked up + to + and - to -)
If it heats up with nothing else hooked up, you either have a short, or you've hooked up the battery backwards.