Oh I missed your first bit of your post I thought it was new ish. Thermostats can fail and so can heating elements, Try unplugging the T-stat and plug it into a lamp Can you remove the probe? If you can set it beside the light it should come on and shortly shut off again. Try testing the heater too remove the snake and just plug it into the wall and feel it to be sure it is heating. It sounds like it is partially working my guess would be the heating elements but it is 50/50.