Insert your microSD card into a computer. Format it to FAT32 (not exFAT or NTFS). The Z6 bootloader only recognizes FAT32. Use a tool like guiformat if your card is larger than 32GB.
“The new ‘Pure Music Mode’ in firmware v2.1.8 turns off all Android background services. Battery went from 8 to 14 hours.” — Amazon review phinistec z6 firmware update
The general process involves obtaining a firmware pack (roughly 19MB) from Phinistec and applying it through the player's internal menu. Insert your microSD card into a computer
Note: Do not place it in a subfolder or on the SD card unless specifically instructed by support. Initiate Update Disconnect the player safely from the PC. On the Z6, go to Automatic upgrade Firmware update Click the central key to confirm and start the process. Auto-Restart Use a tool like guiformat if your card is larger than 32GB