Chemlawn killed my yard years ago. I called and told them. They said they were sorry. I told them to screw off. That I would find another company that did not kill lawns. Luckily it was Bermuda grass(hearty stuff). I de-thatched(manually) three large trash cans full of dead grass and then let it grow back in. I did have to apply some sand in areas. By the end of the summer, it was back. But I had time to foll with it. If I did not have time, I guess I would have waited for them to kill it more.
thanks for listening to my story that did not help him with his decision.
Your story brings up something that scares me.
NOTHING is growing in the dead spots. No weeds. No grass. No flowers. Nothing. It's arid.
I get the feeling the poison is deep in the soil and that even re-sodding won't help. My only hope may be to lay sod and get out of the house before the buyer/renter notices it dying.