I have an LG G2 (vs980 - Verizon). The digitizer and screen is broken - I can view it, but not submit input.
The device has fastboot and TWRP capabilities, and I can get to ADB from TWRP.
The device previously had USB debugging enabled and was associated with my PC's public key.
It seems the only thing preventing me from accessing the device via ADB while booted normally is LG's 'USB connection type' setting, which defaults to 'as a media device' or 'as an installer'. This phone requires me to choose 'as an internet connection' / 'ethernet' once I hook up the USB cable from the notification panel for ADB debugging to work. As the screen is broken, I cannot do this.
How to I write this setting to the system from recovery mode? Perhaps a build.prop tweak or a sqlite3 edit? (I have sqlite3 on the device; I just enabled my wifi with it).
$ adb shell getprop | grep persist.sys.usb.config [persist.sys.usb.config]: [mtp,adb]
Since I can access ADB from recovery and my rom has a /system/etc/init.d, i can run commands after the system boots from here.
My current plan is to switch ADB to connect over wifi and proceed from there.