Stuck with my solo 4k

Hi I took delivery of the solo 4K and started setting it up and got as far as picking video input/video mode then language and before I could get a chance to choose my tv screen has gone black and saying no signal and the
box won't respond to the remote. When I power off and on again it gets as far as the screen saver and then goes blank again, how do I get to proceed further. I know this is not the normal way it works.

Quote from master G

If you have changed it to full 4k and your tv doesn`t support it you will get a black screen.. Which resolution did you change it too ? Use the minitv to navigate through the menu and change the resolution to something lower..

Master g it changed that quick I was for setting it at 720 and 4K was maybe the 4th one down but I don't know what happened. I will try the mini screen although it's in a different language but here goes. I will report back.

- - - Updated - - -

I finished up reflashing the box again and everything went ok from there, thanks for your replys Master G and codeman.