Add the lid and set the valve to the sealing position.
Cook on high pressure for 90 minutes.
After the cook time, allow the pressure to release naturally 15 minutes. Then do a quick release to release the remaining pressure from the Instant Pot by moving the valve from the sealing to the venting position.
Then shred the brisket and it's ready to serve!
Notes
*Refrigerate the leftovers in an air tight container for up to 5 days or you can freeze the leftovers for up to 3 months.