Can i get in trouble for selling a fake on offer up?

Sold a an iphone red 7 offer up I had bought
I met up with the man and he examined the phone for about ten minutes before handing me the money 400$. A couple hours later, i get a text message about how the phone are fakes.

He says that he will tell the police that this was a scam. The only thing he has is my cell phone number.
I did not force him to buy the iphone and he adequately examined the iphone before buying.

IPhone 7 volume problem?

So I was just listening to music on my iPhone 7 and all of a sudden the volume glitched all the way up. I tried to turn it down but whenever I would bring it down it would bring it back up. This lasted for about 5 seconds. Then about 3-5 minutes later this happened again except it went to full volume, around half way then to two. Is this just a fluke or is there something wrong? Have any other iPhone 7 users experienced this?

T mobile exchange phones?

My family and I just leased phones with t mobile and my dad got a galaxy s8. He had an iPhone before and got used to it and doesn't like the galaxy. Would t mobile allow him to exchange the galaxy for an iPhone without having to off the galaxy phone and all that? Has anyone had any experiences exchanging a phone with t mobile? It's only been one day so if they let you exchange phones within a certain amount of days we could do that

Bad phone battery even when replaced?

I recently got my iPhone 6 battery replaced because in my iPhone settings it told me the battery needed to be serviced. Once I got it replaced I was happy and thought I wouldn't have to stress about always carrying a charger with me… But it still drains pretty fast even when I'm not on it much? I'm so confused and frustrated