Look into OTHER commands like chmod existing in the ADB commandset then
chmod won't do anything if a whole file system is read-only. To make
All I know is, I did ADB 'pull' on my nephews phone
Was it rooted? That's what I meant by the backup requirement: to root a Nexus 7 tablet, you need to unlock the bootloader (fastboot oem unlock), and that wipes the device.