DIAGNOSIS The burn error is the pot's overheat protection kicking in. The most likely cause is that you don't have enough liquid, or you've got something thick like tomato sauce or starch on the bottom that's scorching before pressure builds.
FIX First, release pressure, unlock, and open the lid. Check the bottom of the inner pot—if there's burnt food stuck, you need to start over. Clean it thoroughly. For the next try, make sure you're using at least 1 cup of thin liquid (water, broth). For thick sauces, always add them on top of other ingredients, never let them touch the bottom of the pot directly. Use the pot-in-pot method if you're worried.
IF THAT DIDN'T WORK The sealing ring might be damaged or not seated correctly, letting steam escape and causing the heating element to overwork. Pop it out, inspect it for tears or food debris stuck in the groove, clean it, and snap it back in securely.
HEADS UP Natural pressure release for 10-15 minutes after cooking can help prevent the burn error on tricky recipes, as it stops the vigorous boiling at the bottom immediately.