Following release of the Spark firmware 1.4.3 end of July 2021, a number of users reported some issues, having no sound coming out of the amp anymore after the firmware update.
In the majority of cases, it it recommended to perform the update procedure 2-3 times to fix the issue.
Be sure to follow the exact procedure, step by step.
In case you still have troubles after multiple update attempt, don’t hesitate to reach out to Positive Grid support team. They’ll probably send you a new updater tool.