First things first, you'll have to explain what happened, Secondly you must give the customer the option to choose whether he/she would prefer to temporarily take the laptop and schedule another time to have the hinge be repaired as you can provide the reason that you have prioritize to fix the functional aspect of the laptop rather than the cosmetic issues of the laptop. Putting yourself in the shoes of the customer whilst picking your statement would help to alleviate the concern or complain from the customer.