Diagnosis
The unit is in standby mode with the lid not fully secured. The triple beep is the safety alert. The lid sensor isn't engaged.
How to Fix It
Turn the unit off. Lift the lid completely and then firmly close it. You must hear a distinct click. The lid handle should sit flush. Press your cooking function button again. The timer should start.
If That Didn't Work
Check the lid's rear hinge area. Look for food debris or grease blocking the black plastic latch mechanism. Clean it with a dry cloth. Ensure the basket is correctly seated and not tilted.
Heads Up
Never force the lid closed. If the click isn't happening, the lid latch or the micro-switch in the base might be faulty. Contact Instant Pot support.