Help with a Z9 mini

Hello everybody,
I have an Antminer Z9 Mini and would like to overclocking it a bit. Unfortunately, the previous owner installed 2019 firmware and so it can no longer be done using the HTML version. can someone tell me if there is another option? Maybe also about the downgrade of the firmware?
thank you for your effort
Greetings Tobi

There’s a small reset button on the front of the device, maybe that could reset to factory?