I just searched MRegister Mode on google took me back here to a different user who did the same thing
Keep trying man, this board wont beat you
dont take the easy road and send it back, figure it out!
There is like 3 or 4 ways to get back up, download balenaetcher and try the Krescue, turn on wifi and run the file from the Krescue list
SDcard force flash https://docs.khadas.com/vim3/UpgradeViaTFBurningCard.html
Try em all