Grohe SmartControl self destruct?

[Sewer Rat]

I installed a Grohe triple function SmartControl in our shower several years ago. It has worked fine until today. The hot water side has completely shut down. I get cold water, but the flow drops to zero as I adjust the control towards the hot side. The hot water supply to the bathroom sink is still good and there aren't any valves that could be accidentally turned off in the line feeding the shower. Just coincidentally, I was troubleshooting an intermittent problem on my boiler a few days ago and had adjusted my hot water temp up to force the boiler on. Decided I liked the hotter water (130) at the kitchen sink so left it there. I don't have any kids or old people in the house, so I'm comfortable with that temp.

Does anybody know if the thermo control valve "self destructs" to prevent dummies like me from scalding themselves in the shower? Note that this worked fine yesterday but I don't get a drop of hot water out of it today. I suppose it's possible that a large chunk of something suddenly caused a 100% blockage, but I'm rarely that lucky.

Thanks for any ideas!

 

[Breplum]

Do you still have the "flush plug" ? That would sure help.
Do you have internal stops, if so, see about opening things up.
Or shut house water and pull the thermocartridge completely and check visually.