PBP won’t boot from eMMC after Debian update / Tow-Boot installer won’t boot from SD

[Pino64]

To chroot I'm trying to follow the steps I found here:
https://superuser.com/questions/111152/w...stallation
I'm already getting stuck at the second step though:

/$ sudo mount -t ext4 /dev/mmcblk2p6 /mnt
mount: /mnt: /dev/mmcblk2p6 already mounted or mount point busy.

I unmounted mmcblk2p6 but keep getting the same reply.

EDIT:
Okay, that was because the LUKS filesystem was still unlocked..

With guidance from:
https://archived.forum.manjaro.org/t/how...tion/10760

cd /
/$ sudo cryptsetup open --type luks /dev/mmcblk2p6 crypto
/$ sudo mount /dev/mapper/crypto /mnt
/$ sudo mount /dev/mmcblk2p5 /mnt/boot
/$ sudo mount /dev/mmcblk2p4 /mnt/boot/efi
/$ sudo mount -t proc proc /mnt/proc
/$ sudo mount -t sysfs sys /mnt/sys
/$ sudo mount -o bind /dev /mnt/dev
/$ sudo mount -o bind /run /mnt/run
/$ sudo mount -t devpts pts /mnt/dev/pts/
/$ sudo cp /etc/resolv.conf /mnt/etc/resolv.conf
/$ sudo chroot /mnt
root@PBPD11:/#