For anyone trying to use MrChromeBox to change the firmware on a CB715, you have to disconnect the battery, however, when you go to boot up with the battery disconnected with the USB power, it won’t boot up. After doing this, remove the USB power, plug the battery back in, plug in the USB power again and it will start with the write-protect off. It was different than I expected and wanted to give clarification on this model.