Hurray!!
I eventually got it working!!
Link in previous post is relevant. In /system/etc/prop.default , ro.debuggable should be set to 0 .
Step-by-step this gives:
- install ADB on computer
- smartphone: enable developer mode, in settings/system/developer options, enable USB debugging, and enable ADB as root
- connect smartphone to computer via USB
- smartphone: activate debugging mode in notification bar
- open a command-line console on computer
type:
adb root
cat /proc/mounts | grep system
to locate system mountpoint (something like “/dev/block/platform/XXXXXXXX.ufs/by-name/system”)
mount it with write permissions:
mount -o rw,remount /dev/block/platform/XXXXXXXXX.ufs/by-name/system
edit prop.default:
nano /system/etc/prop.default
in which you set:
ro.debuggable=0
exit and you’re done.
This ro.debuggable option enables ADB as root. So, being set to “0” this option becomes hidden in developer options. I just hope it won’t lead to future issues, but this looks rather riskless to me.