Possibility of flashing a new ROM to a stolen Nexus Last weekend a Parisian pickpocket stole my Nexus 5X.


Not rooted
Locked bootloader (not modified in any way)
Fully encrypted (and backed up)
Locked (fingerprint/pattern)
Updated to Oreo and current security patches
USB Debugging turned on [MTP] (unfortunately)


Aside from the pattern lock and enabled USB debugging being weak spots, what are the chances of him successfully wiping this device and flashing a new ROM to it? In the real world, how useless will this stolen phone be to him?
It is possible to use the phone without flashing a new rom, or a bootloader unlock.

The thief can reset your phone using the recovery mode


Recovery mode can be entered by powering down the device and then pressing the volume down and power button simultaneously.
then he will have an option to wipe data/factory reset the phone.
Upon reboot he will be greeted with Factory Reset Protection.
The FRP can be bypassed on 8.0 oreo using the method here