10. How to update the firmware of RETRO NANO?

Online upgrade：
Set the RETRO NANO to the BT mode and connect to the mobile phone via Bluetooth. Download the Fiio Control App on your phone and connect the RETRO NANO. On the RETRO NANO page, click the settings pattern in the upper right corner, find "Firmware Upgrade", find "Online Upgrade" and click it. If RETRO NANO has available Bluetooth firmware, a pop-up window will prompt you for the new version. Click OK to upgrade.

Local upgrade:
1. Import the "RETRO NANO_Vxxx.bin" firmware into the mobile phone;
2.Set the RETRO NANO to the BT mode and connect to the mobile phone via Bluetooth. Download the Fiio Control App on your phone and connect the RETRO NANO. On the RETRO NANO page, click the settings pattern in the upper right corner, find "Firmware Upgrade", find "Local Upgrade", select the firmware imported to the phone, and start upgrading the firmware.
Note: During the firmware upgrade process, please do not leave the upgrade interface, otherwise the upgrade may fail! The upgrade may take a long time, please be patient. If the upgrade fails, you can try again.

How to check the firmware version?
Long press the multi-function button [M] and go to menu settings-version to view the firmware version.