If you have an issue with gpg verification of packages the instructions are slightly different to recover as the signing keys are different:
pacman-key --init pacman-key --populate archlinuxarm
This is if you get errors like:
error: mutt: signature from "Arch Linux ARM Build System <firstname.lastname@example.org>" is unknown trust :: File /var/cache/pacman/pkg/mutt-1.10.0-1-aarch64.pkg.tar.xz is corrupted (invalid or corrupted package (PGP signature)). Do you want to delete it? [Y/n] y error: failed to commit transaction (invalid or corrupted package (PGP signature)) Errors occurred, no packages were upgraded.