Won't switch on

[Lord of Hog]

My knowledge on this subject is minimal so please forgive me if it transpires I've made basic errors.

I have a Pure Highway H260DBi fitted. Not flash but it does the job. However a few days ago it refused to switch on when I pushed the button. I've checked all the fuses and they seem to be ok. It appears to have power as, when I took off the detachable front and pushed the "reset" button, I could hear a whirring from the CD motor.

It has done this once before about a month ago, on which occasion it started to work again for no apparent reason after a couple of days.

Is there something obvious that I'm missing? Or is it time to replace it? If the latter then will any single-DIN unit accept the current wiring or will I need to fiddle about?

Sorry if I appear not to have a clue but it's because I don't.

(By the way the unit isn't fitted to my Rover but is in one of my other vehicles, but I don't suppose that makes any difference re diagnosis).

PS. I've read a couple of articles that suggest that it may be something to do with the cold weather. Last time it happened I drove about 25 miles with the heater on and then left the car sitting in the sun all day and everything was working again when I got back into it to go home. Coincidence?