What do I do when I lose my PIN-code?

When you lose or forget your PIN code, you can reset the ZERO and restore your backup.
To reset your ZERO, enter 10 wrong PIN attempts. The device will wipe itself and will be restored to factory settings.

After resetting your ZERO, you can set it up again and import your wallet using your backup.
For this, see: 

After the import, you can add your coins to the ZERO's dashboard again. And before synchronising with the LIQUID app, you'll need to remove the previous account via the 'unsync' option in the app settings.