И в мануале на 5-ой странице:
Summary of TF card upgrade procedure:
1.Copy the x1.fw file provided by FiiO into the root directory of a TF card in FAT32 format;
2.Turn off the X1 and insert the TF card into the slot of the X1;
3.Hold the power button while holding the Shortcuts key (upper left key of the X keygroup)
to turn on the X1 in firmware update mode. The following firmware update dialogs will
appear and after the update is complete, the player will restart automatically.
•After the update process is complete, please delete the x1.fw file from the TF card and
update the media li-brary.