You're probably used to seeing the CAMERABOOT drive when loading CircuitPython or Arduino. The CAMERABOOT drive is part of the UF2 bootloader and allows you to drag and drop files, such as CircuitPython.  However, the application in this guide uses a large partition size, which overwrites the UF2 bootloader present on the MEMENTO.

This means that after installing the facial detection application, double-tapping the RESET button will not put your MEMENTO into bootloader mode. 

However, you can get your MEMENTO back to "normal" by writing a new binary application to the board that repairs your board's UF2 bootloader and performs a factory reset: