If it begins to smoke with only the B+, ground and remote connected, the power supply transistors have likely failed.

The protection light generally won't come on if the power supply is blown because the supply must be working for the protection circuit (which protects the output transistors) to engage.

The power light may be connected to the B+ side of the power supply. If that's the case, the power light will illuminate even if the amp is inoperative.

Let me know if you have any other questions.