Do not user “vga=” parameter, it is deprecated. Edit /etc/default/grub, and uncomment:

GRUB_GFXMODE=640x480

Edit /etc/grub.d/00_header search for:

set gfxmode=${GRUB_GFXMODE}

on the next line, insert:

set gfxpayload=keep

verify that the new line is before insmod gfxterm

# update-grub2
# reboot