I can't help with the question as I'm too new of an owner to know anything. I hate to ask what may be a question with an obvious answer but how do you do the reboot?
There is a little pin hole at the bottom of the screen. Use a paper clip or Sim removal tool from a cell phone.
OP, when you say you can't control the water heater, do you mean the control buttons don't appear in the app or that they are there but you can't toggle them on/off?
Linear Mode
