Help: How to Clean a Burned Pan?

So I was trying to cook some of my frozen stuffed quinoa cabbages for lunch, damn those cravings, and because it was taking forever to cook I decided to increase the heat underneath my favourite pot a bit. I turned away for a moment then the smell of black smoke brought me back to the now burning pot. I managed to save my lunch, it was quite good and thankfully had no hint of smoke to it, but the bottom of the pan was charred and had slices of potatoes stuck stubbornly to it, unwilling to go.

This pot in particular is my absolute favourite. It is of a very thick and very heavy stainless steel and wasn’t cheap to purchase. Most of my other cooking pots are from Ikea but not this one so throwing it out is simply out of the question. This is meant to stay and serve as an inheritance to future generations.

That being said, I’m at loss on how to remove this thick layer of crispy black burnt layer at the bottom. I tried boiling the pot with some strong cooking detergent and water, I tried rubbing at it with a metal seam sponge thingy -we call it seam in Kuwait, I’m not sure what its universally called though- and all I managed to do is scrub away the burnt potato slices resulting in the mess above :’(

I want my favourite pot back! I am terribly sorry, my dear pot, to have burnt you but I wish you’d cooperate and let go of that stubborn layer of whatever it is that is clinging to your base. I am seriously contemplating using a detergent that we use as a rust remover just to see if it would work or not but I thought I’d ask first and see if anyone has any tried and tested methods of scrubbing a badly burnt bottom of pan clean? Help?