I have the same issue, I ordered a pre flashed controller and dashboard from a guy on eBay in Washington state. I should be able to install them and then flash a custom firmware. Will keep you posted. It cost me $89 for the flashed dashboard and esc/controller.

I would like to know the answer to this as well. I bought 2 bird es1-300 scooters from Sam's club, added external batteries but can not flash a custom firmware because I have firmware 1.4.9, I believe that's why I can not flash it with esdowng or any other flasher. It fails to flash every time. I or...