Is returning it to a lower court overturning a ruling?

This sounds more like as described - "redo it". Overturning would be this court literally "over turning" and saying adblock is piracy.

No. This is how the legal system works. When you appeal to a higher court, they can make a call themselves when massive mistakes were made at the lower level or they can say the lower court overlooked something and then make them redo their work. It's a convenient choice for the higher judges not to have to do more work themselves. But it's part of the process.