How to properly install the bootloader (grub2)?

Question

Debian

Debian 9 was installed on an encrypted partition as follows: in an encrypted LVM partition, root and swap in it, /boot on a separate partition and unencrypted. This was done during installation, from a regular installer. Then it was necessary to install windows on the computer (at work). To restore grub, I did the following: booted from the system installed on an external HDD (connected via USB), decrypted the root mounted to /mnt, and /boot mounted to /mnt/boot. after that, I executed the following commands:
sudo grub-install --root-directory=/mnt /dev/sda
and
sudo update-grub --output=/mnt/boot/grub/grub.cfg
After that, the following is displayed in the boot:
and the OS does not boot:

what configs (and how) need to be edited so that everything works as after installation (turned it on, entered the encryption password, logged in, work)?
PS I apologize for the quality of the photo, it could not have been better

Answer 1

the last couple of times I helped out with a live cd and installed boot-repair from it ...
but it seems that everything is correct for you, but the UID of the disk is not correct.