Buying and Selling: Discovering Another Defect After Taking Possession
Practical Laws of Islam as per the teachings of Ayatullah Sistani
Ruling 2145
If a buyer realises that an item has a defect and after taking possession of the item another defect is discovered, he cannot annul the transaction. However, he can claim the difference in price between a non-defective item and a defective one. But if he buys a defective animal and discovers another defect before the passage of time for the option with animals, which is three days,[1] he can return it even if he has taken possession of the animal. Also, if [in a particular transaction] only the buyer has the right to annul the transaction until a particular period and during that period another defect is discovered, he can annul the transaction even though he has taken possession of the item.
-Ayatullah Sistani, Practical Laws of Islam, Buying and Selling
See Ruling 2134, case 10.