MMI shuts off after starting up

[Barondeux]

Hi guys 

My a4 2015 multimedia mmi started misbehaving, the dab stations on the radio started disappearing no reception so switched to fm then over a few days these dropped off no reception 

i thought bad earth antenna so then tried to play media via phone, I noticed the mmi was taking a while to come on, it now only displays splash screen then shuts off.

it sometimes starts nav initialising but shuts off pretty quick and black screens.

i took out radio unit from boot took it apart to check for bulging caps and dry joints but all looked good.

now I’m stuck still feels like a bad wire but not sure what to do next

If it was a fuse it would not work at all 

Thanks