Help please.

We have a Whirlpool ARG 918WP (int F/F) Service number 8534 918 15010 - about 12 yrs old. A few days ago stopped working. We turned mains off and on again and compressor noise seemed to start again - normal noise. Next day realised it had stopped working and was defrosting. Tried all combinations of turning off and waiting different times, but now completely dead. Power lights on, but neither fridge or freezer working and no noises. Model had two thermostats so unlikely that they have both gone at the same time. I understand could be a faulty relay, but will not know unless I order and buy one - about a week. I have tried banging bottom of inside of fridge incase loose connection or relay starting to fail, but completely dead. Whirlpool unhelpful.

Any ideas anyone, is it worth repairing?

Thanks