These commands check the EFI filesystem for errors and recovers them if possible
sudo parted /dev/sdX print
sudo fdisk -l /dev/sdX
sudo sfdisk -l
sudo dumpe2fs /dev/sdX1 | less
sudo dosfsck /dev/sdX1
The ESP (EFI System Partition) is normally a (V)FAT partition with the "boot flag" set, in parted's nomenclature.
Mount an EFI partition
sudo mount /dev/sdX1 /boot/efi
sudo mount -t vfat /dev/sdX1 /boot/efi