HELP! 120 won't start

[whatmore]

Hi all, 

first post here and it's a problem - apologies in advance.

I recently bought an Expert 120 and love it 

That's the good news.

Now the bad. I also bought the preamplifier board for it so that I can run my active subs.
I installed it following these simple instructions: https://vimeo.com/98140701

But now my unit seems to be completely dead. There is power going to it (the little red light is on). But the display is completely blank 

Just wondering if anyone has any ideas. Is there a way to reset the unit for example ?

thanks in advance