Can you negotiate after purchase agreement has been signed?

[Brandon Forgham]

Hi bigger pockets,

Im buying a duplex that i was turned onto by a family member who rents it at the moment. I've done a home inspection and walk through with the inspectors. After inspection i negotiated the price down $1000 and signed the purchase agreement. I am in the process of closing now and got a phone call from my family member stating that there is water coming through a light fixture on the porch, that just started to happen. Can I still negotiate the price down and do a new purchase agreement based on this new info?