The top panel LEDs are flashing because the OTA firmware update is in progress, the product should work after the upgrade is completed. It may have been caused by a previous interruption to an update.

It should be possible to resolve the issue by doing the following:

• Plug in the power cable and wait for at least 5 minutes for the Partybox Ultimate to complete the update.
• If the Partybox Ultimate stops flashing, but cannot power on, then perform a factory reset by pressing the two buttons below for more than 10 seconds: Moment (heart symbol) and Play (or through the JBL One app). After this has been done, press the Power button.