What is the ruling of the Shari'ah concerning selling a used laptop while concealing its defects, knowing that the selling price is lower than the market price, in addition to giving the buyer extra items that were not agreed upon, with the buyer wishing to annul the sale after discovering the defects, and the seller having already spent the sale price?

The seller made a mistake by concealing the defects of the device from the buyer, based on the Prophet's (peace be upon him) saying: "If they are truthful and open, their transaction will be blessed, but if they lie and conceal, the blessing of their transaction will be effaced." If the defect affects the value or defeats a purpose, the buyer has the option to return the device and get a full refund. The fact that the price was below market value or that the buyer received other items does not change the ruling.