If it's that bad, I think a new back window is in order.. I don't know if you can rebuild the whole grid.From how i read it... he REMOVED all of the defroster lines from the rear windshield....
Thats what i figured as well... stinks man... but if you removed ALL lines... doubt there is any way to go back... you need new rear hatch glass.You can touch up small breaks with some paint like liquid per the directions in your manual, but drawing completely new lines... I doubt that possible.
Time to track down a new hatch/rear glass.