Boy, did I buy some FMB130 modules, and put one on the test bench to learn more about them. Turns out I changed the config pin which is "5555", and now I don't remember what pin I put. I tried a few until I blocked the equipment. It turns out that this company Teltonika does not offer any support to the end user, who is the one who pays for the equipment. I can't get that unlock key from anyone. It was the biggest disappointment trying to work with this brand, despite the quality of equipment and software.
Attendants do not have any training.