Motorola G2 - "erasing screen" and reboot (over and over)
While running the screen "erasing", press the "Volume Down" button, and after the reboot occasioned by the "loop", the Bootloader screen will appear, and then you can select the "Recovery" mode as usual, giving you  the normal menu screen (wipe cache, factory reset, mount /sys, update from SD card, update from ADB, and so on). With the last option, I was able to manually update the Android, using "adb" commands via terminal + using a update package (for example: http://androidhost.org/plvIU).