Start by unhooking your plugs at the window and check continuity from both plugs up to where you made the repair the first time. If you have juice at the original repair and continuity all the way to the plugs it has to be in the glass.
How do these things go bad "in the glass"? Is that from harsh cleaning of the interior glass? My 2002 Rear Defroster still works fine at 242,000 miles, but you can count on one hand the number of times I've cleaned the rear window interior glass over almost 20 years now (with Windex and paper towels)
Well there was no continuity in the wire. Found a buddy with a power probe wireless short finder. That thing was slick.There was a kink in the factory harness under the back seat. It must have generated enough heat over the years that it just got brittle and broke the wire. I replaced about a 2 foot section that was getting hard so it should outlast the rest of the car now.
As for the grid going bad in the windeow. Every time I have see them go bad was from other issues that caused the defroster to stop working to begin with and then people cant figure it out so they take an ice scraper to the inside. Junk every time