So after some further testing I've found out the following:
The system will only power back on from a shutdown if the a/c power adapter is disconnected prior to shutting down or after shutting down.

For some strange reason, if the a/c unit is plugged in when the unit is shutdown, the power button won't work when you try to power the unit back on (unless you unplug the a/c adapter for about 10 seconds).

I've tried messing with various settings in the bios but nothing seems to change this behavior.
If anyone has any suggests, I'm all ears! Thanks!