booting from secondary SSD - /dev/sdb

At first, installed on the secondary drive (SSD), and Linux Mint automatically wrote grub to the SSD. But when booted, grub was loaded from the primary drive. First, I tried update-grub which worked - the new install was also seen. But when I reformatted the primary hard disk, a grub rescue> prompt was seen. In my case, I did not really need to do the grub rescue - instead, I needed to go into the bios by pressing enter on a USB keyboard during boot (since the built-in keyboard enter key was broken), then Startup --> Boot --> make the SSD the primary boot device, then save and reboot.