OPZ stuck in upgrade mode

Hi everyone, I’m new to the forum, I’m writing to you with a problem. Today I installed a line module in my OPZ, and updated the firmware, which I could avoid doing as the latest one available was already installed.
The strange thing is that after one session, I turned off the OPZ which was attached to a USB hub. Upon restarting the option it started in upgrade mode. Not knowing what to do, I tried to look for some info, and I installed an old firmware to attempt the rollback. Nothing to do, I have tried several times to install various versions but the result is always the same: My OPZ turns on in upgrade mode, I can’t get out of it. Sorry for the long description, has anyone had a problem like this?
Thank you all