Based on community resources, several official stock firmware versions exist for the Axon M Z999. ONFIX, a firmware repository, catalogs multiple official versions including:
Essential for your Windows PC to communicate with the Qualcomm processor inside the phone.
Custom ROMs are modified versions of Android created by the developer community (such as LineageOS, Resurrection Remix, or AOSP).
Regardless of the firmware chosen, prepare your device to prevent data loss: Save contacts, media, and app data. Charge Device: Ensure at least battery life.