How to switch back a Miele PT7136+ from washhouse mode?

I accidentally put a Miele PT7136+ dryer in washhouse-mode (this is my best translation), where only the four shortcut keys work and the menu is disabled. According to the manual, only the technicians can switch it back. However I can't call them because the machine doesn't belong to me, and the boss would kill me if I tell him what happened...

Does anyone know how could I switch it back myself?

If necessary, I can use the internal RS232 port. I already looked for reset jumper or RAM battery inside, and tried the usual button tricks without success.

Much thanks in advance!