A PLC controls real-world machinery. An incorrect unlock attempt could cause unexpected forces (e.g., a press activating). Always disconnect power to outputs before attempting unlock work.
On S7-200 SMART models, you can create a system reset card using a standard Micro SDHC card and a PC. Inserting this card can force a reset of the CPU parameters. Understanding Protection Levels siemens s7 200 smart password unlock work
This is unreliable (brick risk: high) but has been documented on forums. A PLC controls real-world machinery