Answer to "Touch input broken for a dropped nexus 7"See one of the other posts on cracked screens. Asus repair: $150 +$10 return shipping.
Answer to "What is the U62 pin for?"My best guess would be Antennae??
Answer to "Where to find replacement parts for Nexus 7"Since it is manufactured by Asus, and that is where you would register it, check their website. Of course, they are not going to cover damage under warranty. I know that some of the extended warranty companies cover damage or loss, but it's a little late for that. Here is what I got off of the Asus site. I don't know if this is the number you called, but if not, it's worth a shot. They must sell parts, either that or out of warranty repair. "?RETAIL Product Support ONLY: 1-877-339-2787 (Best Buy USA, OfficeMax, Staples USA, Costco Wholesale, Microsoft, Office Depot, Walmart, Future Shop ) All-in-One, Desktop, Netbook, Notebook or Tablet" From the teardown, it sounds like it's gonna be expensive. I'm surprised that the Gorilla Glass (a Corning product) didn't hold up.