I am using twrp 3.0.2 for backup and restore on my galaxy s4 i9506 and i dont understand some things.
I wanted to be able to switch between 5.0.1 and 4.3 by having backups of both versions.
So i backed up my phone running android 5.0.1. I then wiped my phone and flashed the 4.3 rom. Now my phone is on 4.3.
After that i made a backup of my phone on 4.3. Now i have the backups of 4.3 and 5.0.1.
When i tried to restore the 5.0.1 backup on the 4.3 system, it would get stuck at the "galaxy s4" boot screen. The 4.3 system would only accept 4.3 backups. (likewise, if i flash 5.0.1, it will also only accept 5.0.1 backups)
Furthermore, when i restore the 4.3 backup with a 5.0.1 system, the "galaxy s4" boot screen will be still be the one from 4.3. (the one from 4.3 has vibration while 5.0.1 doesnt).
This also happens when i try to flash custom roms (it gets stuck at the galaxy s4 boot screen, and it is the same screen as the previous OS). Hence, i am unable to flash any custom rom.
I thought that nandroid backups are supposed to restore the entire system to the way it was (exept internal and external sd cards), i dont understand why it does not. I also dont understand why the galaxy s4 boot screen does not change when restoring or flashing custom roms.
I tried to make this as clear as possible, thanks for reading!