Buyer wants to return item I sold as broken for parts/repairs

Hi, I recently sold an IPod to someone with a broken screen - which was listed in the title, shown clearly in pictures and also described in the description. The buyer knew the screen was broken and bought it knowingly for repairs.

Buyer came to my house, inspected, bought and left happy. Later tonight they message me saying the motherboard inside is corroded and that when trying to replace the screen it broke their working replacement (saying that it'll cost them 35 extra to replace) and that they want a partial refund.

I'm just wondering would I be in the right to deny the refund? It's my first time selling on marketplace and I genuinely didn't know about further damage inside, I feel like since i already said it was broken and had been sitting around for awhile therefor I didn't know if there were other issues with it it's on the buyer.