I purchased a module that I encountered during startup. At first I programmed the module via the ST link v2.
Example: E: \ nRF5_SDK_11.0.0_89a8197 \ examples \ peripheral \ blinky \ pca10028 \ s130 \ arm5_no_packs
before programming, Bluetooth was not visible to other devices. After programming, it was not visible to other devices
How can I get the chip back to factory settings with ST Link v2?
Because I feel the memory of the layout is messed up
That's a very old SDK - even for nRF51!
Note that nRF51 are not recommended for new BLE development:
Getting started is always easier if you start with current stuff!