2 Added my own commentary to the referenced post
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Lifted from a similar question elsewhere on StackExchange:

If you have hard water, a soak in vinegar can be helpful. A cooked on veneer of calcium carbonate, or similar water minerals, can make food stick to the surface of the pan very tightly. Vineger will dissolve the stuff completely – Wayfaring Stranger Jul 20 '13 at 12:36

You mention you've already tried vinegar, but Wayfaring Stranger's post points up that the issue in this case is not loss of a nonstick coating, but most likely deposition of minerals from whatever was in the pan when it overheated. When I've overheated pans due to inattention (more times than I care to count), I have found that Barkeeper's Friend and aggressive, thorough scrubbing with a green Scotchbrite pad is the most reliable way to get all of the stains and deposits off. Depending on what was in the pan (proteinaceous or fatty food, for example), sometimes Bon Ami works very well, too.

Lifted from a similar question elsewhere on StackExchange:

If you have hard water, a soak in vinegar can be helpful. A cooked on veneer of calcium carbonate, or similar water minerals, can make food stick to the surface of the pan very tightly. Vineger will dissolve the stuff completely – Wayfaring Stranger Jul 20 '13 at 12:36

Lifted from a similar question elsewhere on StackExchange:

If you have hard water, a soak in vinegar can be helpful. A cooked on veneer of calcium carbonate, or similar water minerals, can make food stick to the surface of the pan very tightly. Vineger will dissolve the stuff completely – Wayfaring Stranger Jul 20 '13 at 12:36

You mention you've already tried vinegar, but Wayfaring Stranger's post points up that the issue in this case is not loss of a nonstick coating, but most likely deposition of minerals from whatever was in the pan when it overheated. When I've overheated pans due to inattention (more times than I care to count), I have found that Barkeeper's Friend and aggressive, thorough scrubbing with a green Scotchbrite pad is the most reliable way to get all of the stains and deposits off. Depending on what was in the pan (proteinaceous or fatty food, for example), sometimes Bon Ami works very well, too.

1
source | link

Lifted from a similar question elsewhere on StackExchange:

If you have hard water, a soak in vinegar can be helpful. A cooked on veneer of calcium carbonate, or similar water minerals, can make food stick to the surface of the pan very tightly. Vineger will dissolve the stuff completely – Wayfaring Stranger Jul 20 '13 at 12:36