well this is a new one for me considering how many android devices i've had in the past. but a device that wont reboot once a usb cable is plugged in is rather new.
so i was flashing a bunch of roms ... some are N and some are marshmallow on my lenovo p1a42 ....
for some reason now if the usb cable is plugged into a pc or even a wall charger and i reboot it -- it just sits still at a black screen .... the moment i unplug the cable it continues to reboot.
one of the roms i flashed had magisk ... although i am not sure if thats the cause or not.
i need to be able to hold the volume up + plug the usb cable to restore stock firmware. i cant do that now because once the cable is plugged in it wont boot.
i tried different usb cables. same issue.
((EDIT: Issue resolved. wiped internal storage + flash/cache/etc))