Did you buy it with a credit card? Check to see if your credit card has additional return/warranty periods.
Or, if you have the time and opportunity, sue the manufacturer in small claims court.
Better yet, tell your friends and family about how the ads start after the return period closed, and encourage everyone not buy that garbage in the first place.
I wrote a guide years ago on blocking them via DNS which loads of people found useful. These days a PiHole is probably a better option.
https://gist.github.com/peteryates/b44b70d19ccd52f62d66cdd4b...