[Q] Display freeze but boot ok with NRT boot temporary

[RFZ]

Hi,
I'm trying to clone my Nexus 7 onto few more devices with NRT Backup + Restore option using Nandroid Backup / booting TWRP temporary.
The devices goes into bootloader mode and the screen freezes at this state. No "booting ... image" is visible, just "Start", "FASTBOOT MODE" etc. However, the device is actually booting up and the complete backup procedure completes fine in background with the bootloader screen still visible.

Restore however does not complete, because (as far as I remember) user interaction is necessary in TWRP which I cannot see.

When I restart the device it boots just fine.

Device: Nexus 7 v2 Wifi with Adroid 4.4.4 KTU84P, Bootloader FLO-04.02, unlocked

Any ideas why the display freezes while running temporary boot images?

 

[RFZ]

Btw. to make it really strange:

If I select "Boot temporary: custom recovery" from NRT with the device being in fastboot already, I can use/see TWRP.
If I select "Boot temporary: custom recovery" from NRT with the device being powered on, the display freezes in fastboot and I cannot use TWRP (but it actually booted, I guess)
If I select "Reboot bootloader" from NRT with the device being on and "Boot temporary: custom recovery" afterwards, I can use/see TWRP.

That's weird...

 

[RFZ]

OK, the strange behavior is caused by the option "fastboot oem off-mode-charge 0".
With "fastboot oem off-mode-charge 1" I can boot TWRP correctly using NRT.

edit: or not... I do have difficulties to reproduce that behavior :/

I do have 10 factory new devices here. The only change I did so far was "fastboot oem off-mode-charge 0"... Reverting that seemed to resolve the problem, but now it happened again.