Do a USB live boot … in order to examine each disk and see what /etc/fstab says v. what file system, if any, is on each partition of each disk.
If it’s only a GRUB problem then grub-mkconfig may fix things (but be careful here because if live booted, you would be trying to fix GRUB on the disk you would like to boot from, not on the USB flash drive that you have booted from).
It is possible that “grub rescue>” can do this without needing a USB live boot but I haven’t spent enough time at that prompt to know its capabilities. So help would probably be a good thing to type.
I have a Debian installed on the other drive
If I press the esc button then I am getting the menu with option which drive to boot from.
I just want to not to have to press the esc during the boot process…
If it were a non-coreboot device, you should in theory be able to just set the preferred drive in the boot manager settings, or through the application efibootmgr (in the terminal after booting into the OS), but… this is coreboot, so…