My one-year old Rheem Hybrid Hot Water Heater (xe50t10hd50u0) is completely dead. Power to the unit is good (full 240v). Screen on the unit is blank. I've pressed the reset button; no help. Unfortunately, Rheem is closed because it is Sunday, so tech support is not available. Is there anything else I can try?
Disconnect the power to the unit and let it sit for 5 min and then repower it. You can either switch off the breaker or pull the plug.
Turns out the motherboard was fried in the unit. Rheem sent a replacement unit (turns out it's the whole screen thing), and problem fixed. I did have to get a Rheem plumber to look at it. Part was free and overnighted to us; I did have to pay for labor, though.