Hey MacMan31,
Power button is fine and working as intended. The button does not stay depressed when on because there is an "auto-sleep" feature and if you do not use the amp for a period of time, it will turn itself off. You can bypass this feature if you like, there is a switch on the back. If you bypass the "auto-sleep", then it will remain on forever.
If you want to turn your amp back on, just push the button again.
Please note: If you are checking out the power button when you get it and you press on/off quickly a number of times...there is about a 3-5 second delay built into the circuit to protect the parts from fast power-cycling. This was not communicated at launch and has caused some confusion, we apologize for this. Just to be certain, we have checked some reports and amps in the field, they are all working as intended!
Thank you all for your interest in this amplifier, we're very pleased that so many of you are already enjoying them and spreading the word.