Hello, My name is Matthew and I will do my best to help you today.
Does it say "screen locked" on the upper right corner near the set temperature?
I did not say that last year when this happened either
when in the locked position it would display this, but let's just double check and make sure. If you press the system button on the far left corner do the bottom row of buttons turn to all blanks?
that's not good. This is how you get into the advanced settings to reset the thermostat and also unlock the screen if it was locked.
The only thing I know of to try and reset the thermostats internal controls if it will not let you into the advanced settings is to take the thermostat off the wall for 5 mins as well as leave the batteries out for this 5 mins. Then try it again.
If you can't get it to reset and the thermostat has been shorted out these thermostats come with a 5 year warranty and there are not many out there older than 5 years as the thermostat hasn't been on the market that long. You may have to pay a little for the contractor to handle the warranty claim and install the new one but the thermostat will be free.
the thermostat did not reset. I guess I will need to pursue my warranty.
Yeah I'm sorry there are no other reset options other than going into the advanced settings. Pressing the system button should change the bottom row to all blanks and then pressing the two buttons directly to the right and left of the center blank button and holding them down gets you into the advanced settings. This should always be able to be done no matter what unless there is a malfunction with the thermostat.
I'm going to give you the links to the installation instructions with these steps to get into the advanced settings and what the settings are as well as the operating manual which has the warranty information at the end of it.