DIAGNOSIS The lid position sensor isn't engaged. The alignment pin on the lid isn't hitting the micro-switch in the handle, or the switch is faulty.
FIX Turn the lid until the arrow on the rim aligns with the unlock symbol on the base. Then turn it further to the lock symbol. You should feel a firm click. The lid handle should align with the base handle.
IF THAT DIDN'T WORK Check for food debris or a warped sealing ring blocking full closure. Clean the rim of the inner pot and the lid's sealing ring channel. Ensure the ring is seated properly.
HEADS UP Do not use force. If the lid doesn't close smoothly, something is obstructing it. Forcing it can break the alignment pin or the sensor switch.