Samsung — note 5

My 1 year old Note5 mobile has suddenly Failed, the screen got green lines, touch stopped working, phone cannot recognize the SIM anymore. The device still have 1 year warranty on it but Samsung refused to repair it under warranty claiming that it has a dent on the side, never the less the dent is very small and it has no relation to the problem as it happened a year back when i first bought the mobile. now they want to charge me $213 to change the screen.