No heat. No images just freezing but off

Hi ruud and welcome, you'll need to give more information for anyone to help. Ok? Good luck

You have to use a meter to see what is happening otherwise you are just guessing and that does not work. Use a volt meter to see if you have power coming in, if yes then check to see if you have control voltage (24 volts), if no then check transformer and see if you have power going in and out. You will have to trace it out until you find where you have a break. You have to learn to use a simple meter.

Batteries in t'stat?