Please contact us through support (at) nitrokey (dot) com - and include your order number (SOxxxxxx) - there we can help you in more detail. Generally there should be a `/var/log/nextbox-update-debian.log` which keeps the output of the update process .... furthermore there is a `/usr/bin/nextbox-update-debian.sh` which is the script to update the system executed once you run click the update button.