DIAGNOSIS The control panel is locked out of pressure mode because it doesn't detect a safe condition. The lid is either not closed fully, not locked, or the float valve is stuck in the "up" position.
FIX Open and firmly re-close the lid. You must hear a distinct click and see the lid lock icon appear on the display. Manually push the float valve (silver pin on top) down until it clicks into its down position. Now try selecting Pressure Cook.
IF THAT DIDN'T WORK There is a fault in the lid lock microswitch mechanism. With the unit unplugged, open and close the lid, listening for a faint click near the hinge. No click means a faulty switch. This requires a service technician.
HEADS UP Never force the lid closed. If it doesn't close smoothly, check for food debris on the rim of the inner pot or the lid's sealing ring groove.