I can't get any hot water in the tub/shower with my moen posi-temp faucet. I have disassembled the everything but the cartridge and cannot get hot water. I can rotate the stem 360 degrees and the water stays cold as it turn on and off. I have confirmed the hot water supply. Do I need a new cartridge?

Try rotating the cartridge 180 degrees

Remove the cartridge and pop the white end-cap off. Pull out the insert and toss it. Reinstall the cartridge. You should get hot water now. Just don't be stupid and scald yourself.

Oops, of course put the white end cap back on... sorry... got ahead of myself.

Well, that is what I tried to do and all that comes out is now luke warm water but no regulation on the hot. Still I do not have any HOT water. This unit was a waste of $. I have had my plumber back twice that installed
The new shower and he wants to replace it , but the problem is that we have to distroy the back shower wall and remove the stall to do it.