Mk3 aftermarket headunit (kenwood) Need help :)

Hey guys,

Just picked my car up the other day and it runs like a dream. Nothing wrong with it all until i pulled up to the bottom of my street after a 95mile trip to get it :p. And the headunit just died out, literally just cut off. So i've been looking around trying to find the problem but have been unsuccessful. But what i have noticed, is when i turn the key to turn the engine over. Just after it engages the battery, if you put more pressure on the key (pushing it into the barrel kinda thing) then it powers the headunit. But if you loosen up on the pressure it just cuts straight back out again.

Any ideas anyone? Not really an electrical wizz :p

Thanks

Kyle