How can i get Burnt apple off of glass Cookware?

i am a PCA and i was making a fresh batch of apple sauce for a client, to help her take pills….

i got distracted, didn’t have enough water in the pot and…BAM…BLACK CRUSTY CHAR COAL CAKED TO THE BOTTOM OF THE POT….and because its glass i can’t just go using steel wool or something to scrap it off…i’ve tried seing soaking it over night twice, and uplastic scrapers and it worked a little bit, but nearly enough

if any one has a secret trick, a handy product, or any help at all…that would be a life saver…if not i have to buy her a new glass pot…which are expensive (unless you have a solution for that instead/also :D)...

in any case thanks every one for your insight

wish me luck