thanks for your answer.
i have news:
the green screen is not a bricked khadas is just when i try to install vim nougat root 170612.
it is an doc error. count 5 6 sec.
long press Power key without release
Short press Reset key and release
Count 5-6 seconds and release the Power key to enter into upgrade mode.
i try with marshallow root 170303… black screen.
i try with usb burning tool normale and administrator mode, normale erase, all errase…
i try erase all emmc with function button and power buton then reset button.
nothing… but one probleme solved i can flahs my khadas vim.