We're out of options then. Seems that the device is definitely checking for a correctly signed ramdisk partition, and we cannot change it unless it's unlocked. :(
anyway, thanks for your time and efforts.
no boot (
I mean follow the commands for manually flashing ramdisk partition like we have been the whole time, but do it with the untouched ramdisk-uboot.img from your firmware zip.
:/ # setenforce 0
:/ # chmod 777 /sy...
I got topjohnwu to take a look at your dtb and he tells me it doesn't have any fstab or verity flags in it, so sadly that probably rules it out as an easy fix to the problem.
Next test would be to just try a repack of your ramdisk.img without a...