How To Fix Grub With Bios Boot?

This will fix on a standard installation, if you do manual partition, ask at the forum!

Boot up with our LiveIso.

mount System to /mnt

You need to know which device is the right one check with sudo fdisk -l

sudo su

/dev/sdXn should be replaced with the right device information, and depending on your installation you may have or have not a seperate /boot partition. If not /boot is a folder under / on the same partition as the filesystem root.

mount /dev/sdXn /mnt >> / root partition

mount /dev/sdXn /mnt/boot >>> /boot partition --> without extra /boot partition you do not need this step!

arch-chroot /mnt

To make shure to get second (dual boot) installation rechecked and put into grub boot menu use os-prober, (for Antergos only system you go directly to grub-mkconfig)

(as root also) If you have dualboot os-prober may takes a long long time to work, the trick here is to mount all other partitions, before using it.

os-prober grub-mkconfig -o /boot/grub/grub.cfg

Reinstall grub:

grub-install --target=i386-pc /dev/sdx

Where /dev/sdXn should be changed to what you get into your system: check with: 

$ sudo fdisk -l 

For  EFI Boot systems go here: https://antergos.com/wiki/miscellaneous/how-to-fix-grub-with-efi-boot/