I tested a little bit the mx4.
- WiFi: OK
- Camera: OK
- Flashlight: OK
- BT connection to Ubuntu Desktop: OK
- lockscreen notifications: OK
- phone crashes when App is allowed to use a device for the first time:
- utorch: Phone crash when allowing access to camera service for the first time (worked after boot)
- unav: phone crash when allowing access to navigation data for the first time (worked after boot)
Not tested: Phonecalls/SMS as the phone does not recognize SIM anymore (hardware defect)