The LINK indicator is lit, but the UPDATE button does not light up and the software cannot be updated.

Check the following.

• When the speaker is being powered by the built-in battery, system software update is not available.
  Connect the speaker to an AC outlet via the USB AC adaptor to update.
  
• When the system software is already the latest version, the UPDATE indicator does not light up.
  NOTE: The software version of the speaker can be viewed from Settings > Other settings of the Music Center (SongPal) application.