Sold old-school TV on Ricardo but buyer demands a part of his money back after he broke it.

I sold an old-school TV on Ricardo, those big heavy square ones from the 90's. I added to the article the size of the TV, the brand, some other aspects and several pictures from different angles with the screen turned on to show potential buyers the TV is functioning as it should.

I messaged the buyer he needs to pick up the TV with at least 2 people due it's size and weight, I mentioned him the exact weight of it. He laughed at me and said he can handle it alone despite I told him I am not strong enough to help him lift this heavy TV two floors downstairs.

He showed up alone anyway and then acted surprised about the size of the TV, thinking it was a flatscreen while the pictures CLEARLY showed otherwise. He didn't took the time to test the TV for it's functioning either and immediately tried to bring it downstairs. I tried to help anyway because he complained he couldn't lift it alone, but because I am not strong enough the TV dropped out of my hand on the stairs, only 5 cm down to the floor from my hands. The plastic corner of the TV got a minor dent from it, the screen got zero damaged and he said it ain't a problem at all and laughed it away again. Eventually we managed to bring the TV downstairs, he loaded the TV in the trunk of his car, wrapped in blankets and drove off.

Now, a week later he messaged me back complaining the sound isn't working from the TV because I dropped it. He added he tried to fix the TV several times by himself but now it ain't working at all anymore and wants a part of his money back because he needs to throw it away.

I haven't replied to him yet because I don't agree at all to give money back for something he broke while I clearly stated I can't help him lifting due it's weight. He also assumed it was a flatscreen despite my picture stayed otherwise. He said if I don't reply soon he's gonna escalate this case.

My question is: What's the worst that can happen to me while it's clearly his fault? I have proof of our text conversations which is everything I wrote above. I'm also on point of moving out of Switzerland and I will close down my Ricardo account along with it.