How to root Doogee Voyager2 DG310 & other mt6582 Devices (permanently) with EngMode?

Question

Using the Mediatek mt6582 SOC Engineering Mode available on the Doogee Voyager2 DG310, with the Debug option User2Root an adb daemon running as root becomes available temporarily.

This will need USB Debugging enabled in the Android Settings.

To access the Engineering Mode on this MT6582 use the Dialer to call a KeyCode: (You have to enter another * to launch the Eng-mode)

The Log and Debugging-Tab:

Choose User2Root:

Click Root:

If you were previously connected with an ADB User Shell, it will by terminated. Opening a new adb shell will get you an adb root prompt. Until the next reboot.

So far so good. With the (temporary) root prompt available, a generic Android 5.X rooting guide should apply now.

I tried:

• Downloading the latest Koush OpenSource SU-package from F-Droid
• Extract su from the APK and adb push it to /sdcard/Download/
• adb push the APK to /sdcard/Download/
• Login as root with adb shell
  • Remount /system Read-Write
  • Copy/move su to /system/bin/
  • chmod 4755 /system/bin/su
  • chown root:shell /system/bin/su
  • Remount /system Read-Only
  • Attempts to run su result in this: error: only position independent executables (PIE) are supported.
• Installing the APK before, or after attempting to run su succeeds, but complains about the su binary being out of date.

So, where would I find a newer, clean, "PIE" su binary? Or am I going about this the wrong way, and there is a newer 'Generic 5.X Temp-Root to Perm-Root' Procedure?