Electric Dimplex Storage Heater?

Hi - I also have dimplex storage heater which stopped working, but no heat at all - just cold. Does anyone know if this could be caused by one of the elements not working - would this mean all the elements would be effected and not heat up at all - or could it be due to thermostat, bearing in mind my storage heater is the old grey model not the newer white one?

I plan on getting part and fixing myself as instructions has diagram of the parts inside, and I am quite handy at DIY stuff.

Thanks for any advice