My flat top eletric stove use too clean up good with
That polish they sell for flat tops but stove is older
Now and front burners don't clean is there a way to
Get black stains off

I was recently surprised to see that leaving a lot of water and some drizzled dish detergent on the top for a few hours cleaned the really stuck on stains well, with just a 3M pad.

You can go to an AC/refrigeration supply house and get some alkali cleaner and dilute 50-50. Wear gloves, face shield, and a plastic apron because it's liquid sodium hydroxide.