╰─$ sudo bless -mount / -firmware /Users/andrei/MBP114.fd  --verbose -recovery
EFI found at IODeviceTree:/efi
Will need to copy 8388608 bytes to EFI system partition
No auxiliary booter partition required
System partition found
Preferred system partition found: disk0s1
Returning booter information dictionary:
{
    "Auxiliary Partitions" =     (
    );
    "Data Partitions" =     (
        disk1s5s1
    );
    "Preboot Volumes" =     (
        disk1s2
    );
    "System Partitions" =     (
        disk0s1
    );
}
Substituting ESP disk0s1
Mounting at /Volumes/bless.3AyI
Executing "/sbin/mount"
mount_msdos: /dev/disk0s1: Resource busy
mount: /Volumes/bless.3AyI failed with 71
Returned 18176
/sbin/mount returned non-0 exit status
Failed to determine auxiliary partition mountpoint for disk0s1
Error while writing firmware updater for EFI