Defective products sold to public

I bought a Playstation online. The store seling it was Cash Crusaders. I went to the store to fetch it there as they said I should fetch it there. They told me to bring it within 7 days for a full refund if it gave me any issues. The issues started about two weeks of having the Playstation 4. It would freeze, restart and then format itself. I then had a closer look at the product physically. This is a Playstation that should have never been sold, it had so many dents and this made me question the state of the product they sold me. I then took it to the store last week to show them this. The manager there told me that it's a software issue and they won't fix it and I should fix. He then said as procedure, he would take it in for a check to see what's up with the Playstation. The product they sold me was highly defective and now they don't want to take their product and refund me. I dont have an issue with them fixing it but the product is defective and you can see it has fell many times or been opened. That product was very defective and it should not have been sold to. They never disclosed the issues prior to me selling it as it was an online sale