MVP-5200i factory reset

I've a MVP-5200i panel that ist locked completely. The panel starts and I can play with the current program in it. So the panel seems to be ok.
If I try to switch to setup by pressing the middle button, the setup does not appear. The button seems to work, because pushing it about 30 seconds switches off the panel.
I tried to connect the panel via USB, but had no luck. The NDIS network appears, but I'm unable to access the panel. Interestingly the second panel of the same type works flawlessly but connecting it over USB does also not work. I saw in the setup of the 2nd panel, that it's USB IP address is set to 172.16.0.2. So I set the NDIS network manually to this address range by setting the virtual network to 172.16.0.1. This doesn't work also. None of the 2 panels answers on the USB virtual network.

Is there a way to reset a panel to factory defaults even if I'm not able to enter setup?
How to access the panel over USB virtual network? What did I made wrong?

BTW: My virtual NDIS network should work, because accessing a MIO-R5 works.