I have a two year old water heater with an electric thermostat attched to the front of the water heater. To change the temp you have to push both the aarows (one blue one red) and hold for about 3 seconds then the LED lights appear and you can change the setting. What has been happening since I left for vacation, I can change the temp to a higher degree but after about 2 minutes it automatically switches back to the vacation setting and simultaneously the old higher setting. Then the buttons won't work and I have to shut it off at the breaker to start the process all over again. I have no manual (not sure what happened to it). Any thoughts?

Before we can help we need to know the make and model of the water heater. Regards, Tom