sudomod

So I finally assembled my MintyPi Lite. Soldering is good and continuity was tested - all seemed to be fine.
So however, if I power on my MintyPi using a Type-C Cable + Phonecharger it will stay on, but as soon as I want to screw everything together and get it into the tin it starts with a white screen which is followed by a quick Retropie-Logo and then again a white screen, so its bootlooping.

Has anyone encountered a smiliar issues?

Thanks in advance.