Fiio M15S - Firmware Upgrade and Technical Support; Firmware Upgrade Methods

Online upgrade
If a new firmware is available and can be detected (with the M15S connected
to an available internet), an upgrade notification will show up in the notification
center. Tap on it to enter the update menu for the online upgrade. If there's no
upgrade notification showing up, you can go to the "Technical
Support->Firmware Upgrade" menu, and tap the "Check for updates" icon to
check manually.
Local upgrade
Also, the M15S can be upgraded locally by a firmware package. Download the
firmware package file from FiiO website, and copy it to the internal storage of
the M15S or an SD card. Go to the "Technical Support->Firmware
Upgrade->Local Upgrade" menu, and find the firmware package file to start the
upgrade.
Notes:
1.Do not unzip the firmware package file.