You could try talking to these people - with a more comprehensive fault description: http://www.satcure.co.uk/tech/humax.htm

acp
April 2017

Impossible fault description - either it's permanently on and will not switch off - or it's off and will not switch on.

I suspect that it's off and will not switch on - I suspect - I can only guess - that there's either no mains power to it or the internal power supply has failed.

Good Luck...
April 2017