Volume keeps Increasing

So I have the Polk Magnifi Max SR connected to my LG 55LB7200 Smart TV. It’s worked fine for about a year, and now it won’t connect to my TV via ARC, but it will through Optical. Furthermore the Power button and Source button does not work on the SB. Finally, when connected by Optical, the volume will automatically increase to a much louder volume after about 2 minutes. I have to continuously decrease the volume every 2-3 minutes. I’ve tried to hold the reset button for 15 seconds, but nothing happens. I’ve tried to hold the Source button and the volume button s for 15 seconds, but nothing happens. Can anyone offer guidance on how to fix these problems?

Thanks!