Reinstall grub2
On Software RAID
Prepare chroot
mount /dev/md2 /mnt mount /dev/md1 /mnt/boot mount -t dev -o bind /dev /mnt/dev mount -t proc -o bind /proc /mnt/proc mount -t sys -o bind /sys /mnt/sys chroot /mnt
Install grub2
grub2-install /dev/sda
Check if Grub was written in MBR
dd bs=512 count=1 if=/dev/sda 2>/dev/null | strings|grep GRUB
Check Grub 2 for the kernel line
egrep ^menuentry /etc/grub2.cfg | cut -f 2 -d \'
Set new kernel as default boot entry
grub2-set-default 1
Check current boot entry
grub2-editenv list