How do I calibrate a Totaline thermostat?

Our thermostat is not reading correctly

how can I calibrate it? I searched the Totaline site and it seems like this particular product is not listed (and I can not find the model of this product), and all the instructions of holding down one of several keys did not work for us. Does anyone happen to know how to calibrate this?

Also, it is showing "E3" message after my previous failed attempts

Thank you in advance and it would be a great help in this cold weather…