"error: symbol 'efi_wrap_1' not found"

Hello again ! So I chrooted in my system thanks to this post

and try the command

downgrade kbd

but the package doesn’t seems to work because it tells me

sh-5.1# downgrade kbd

and then it asks me which packages of kbd do I want to install (I choose kbd 2.6.1-1).
But then this happens:

error: failed to init transaction (unable to lock database)
error: could not lock database: File exists
    if you're sure a package manager is not already
    running, you can remove /var/lib/pacman/db.lck
sh-5.1#

So I tried to install it via pacman into the chroot by doing this

sh-5.1# sudo pacman -Sy
:: Synchronizing package databases ...
error: failed to synchronize all databases (unable to lock database)
sh-5.1#

So I wanted to install it on my live usb and then chroot to use it, but it doesn’t seems to work either.
I tried to search some information about downgrade kbd into a chroot but I didn’t find anything.

Can you help me more about this please ?