Faulty open button after teardown

I took my PS4 apart to clean out the fan and apply some better thermal paste. All successful, the device powers on and plays games nice and quiet now.

The only problem is the "open" button doesn't work any more. When touching it the CD doesn't eject. I've managed to eject discs by using the manual screw method, but would really like the button to work properly.

I've noticed on the inside of the lower casing there is a small metal contact that seems like it should make contact with something else. I've tried beinding it out a bit and putting it back together, but still doesn't work.

Has anyone had this issue or have any ideas?

Many thanks.