White Pimp
Newbie
The reboot disemmcwp command doesn't affect your ability to change the DPI.
IF the reboot disemmcwp command works (and that's a big IF) what it actually does is allow you to remount the system partition as read/write (r/w) instead of being read only (ro). This doesn't even come into play until you root the phone.
Changing the DPI via adb commands modifies a file that is generated on the userdata partition (the partition where all your downloaded apps and your internal storage are located) and doesn't require root or system rw.
When rooting the ZMAX that I had, I had to use this command in order for Kingroot to achieve root itself.