• https://www.chromium.org/chromium-os/developer-information-for-chrome-os-devices/samsung-arm-chromebook

bricked, recovery doesn't help

This chromebook reports that it wants to do recovery, but inserting (few different) usb sticks generated using http://www.google.com/chromeos/recovery instructions doesn't help

https://dl.google.com/dl/edgedl/chromeos/recovery/linux_recovery.sh

custom firmware

• https://www.chromium.org/chromium-os/developer-information-for-chrome-os-devices/custom-firmware
•