S7-1200 Password Unlock Fix -
Wait for the maintenance or RUN/STOP LEDs to finish flashing (usually the RUN/STOP LED will blink or stay solid STOP).
Insert the memory card into a PC and ensure it is empty. You may need to delete any existing .S7S files or folders from it. Power off the S7-1200 CPU. Insert the empty memory card into the CPU's card slot. S7-1200 Password Unlock
A Siemens-branded memory card (2MB or larger). Procedure: Wait for the maintenance or RUN/STOP LEDs to
Power off the CPU again and before restarting. S7-1200 Password Unlock