ISN code from SIEMENS ME5.2.1 can be extracted from 29F200B Flash

Use any suitable programmer. DO NOT USE Galleto CMD or similar

Flash listed on picture in red rectangular

Take out the Flash from the board, insert into programmer and read it.

Run ISN Editor, select BMW, select ME5.2.1, upload read dump and you will see ISN with VIN together.

Upload EWS dump and you will see ISN with VIN stored in EWS. Press DME-EWS button and ISN Editor transfers ISN from DME into EWS, after this press save dump and rewrite synchronized EWS dump back to EWS.

For ME5.2.1, its possible to change VIN only, but not ISN