When your android system has turned on
You have to press Alt and f1 keys together on your keyboard. It will open a terminal like Linux shell
Now enter these commands to edit configuration
mkdir /mnt/sda
mount /dev/block/sda1 /mnt/sda
vi /mnt/sda/grub/menu.lst
To edit press i key on the keyboard replace quiet to nomodeset xforcevesa if you have not done it until now. Because you can make sure, that it will boot. At the end of the line add UVESA_MODE=yourdesiredresolution as example UVESA_MODE=1280x720
Now enter these keys serial
Escape
:w
Enter
:q
Enter
Now type in reboot and press enter