Just finished meeting with a client who lost 10gb of data on their Android device when another tech support provider tried to resolve a boot failure.

They'd managed, just before traveling, to fill internal storage sufficiently to disrupt basic operations; then found they couldn't remove files from device because of Marshmallow's lockdown of the file system.

So they were forced to travel with their phone in that condition, and the system failed. Now they're getting Activation & SIM card errors.