Power & Source of Big Ideas

When ever attempting to root device when using either android 7.1 and 8.1 (images on from download), i gain root but after rebooting i get a black screen. Any suggestions?
hey guys, first time messing with SBCs, figured id jump into it. Im trying to build a new img for my NanoPi M4, im trying to have it be a full Kali Linux but off of the Wiki i feel like im missing something? anyone have any history of this that may shed some light. THANKS!