MacBook Air won't turn off with power button

I just had a battery related problem with my Macbook Air. Had to replace it to get it working again. Everything seems to fine now except the machine will not turn off using the power button. It does turn on just fine with it, but not off no matter how long I hold it down. I’m currently in target disk mode with no way out so I’ve plugged in a few devices to run the battery down to zero so it will restart. Any suggestions in the next few hours would be great.