Quoting 7TOM: Hi I suspect the damage would not render the whole screen inoperative.Continuity is not the best check as it would come up ok if only one element was working check the live and earth when circuit is under load ( screen on) you should have battery voltage one side and less than 0.3 volts on the earth side.
and you will have whether heat elements are OC or not, its unlikely the chip will have damaged any elements but at worst it would only be 2 of them so the rest would work, certainly check for continuity, if you have continuity ( some low resistance probably less thn 5 ohms) if OK, check voltage on both screeen contacts, should be 12v and zero, no 12 v = problem with feed, 12v on both sides = problem with earth, 12v on one side and 0v on other side = you lying to us and its working 😬
Tim