Hi there,
Welcome to the Sony community.
Please try the following steps -
Turn off the unit, and remove all speaker wires from the back. Then turn the device back on and check if the issue is resolved. If it is still having the same issue, turn off the device again leave it off for at least 30 minutes before turning it on again.
Inspect the speaker cords. If a cord is frayed or in contact with another terminal, an error will occur. Fix the connection to prevent a short circuit.
If the warning message is still appearing I would recommend getting in touch with the support team here.
Best wishes,
Sean Mc
