I cannot eject Discs

This is a common issue that can be fixed quite easily by following the steps below;

Non-tear-down Repair

1. Turn off your PS4 by holding the power button until the system shuts off completely.
2. Unplug all of the cords that are connected to your PS4 from the system directly.
3. Place the PS4 vertically. The disc usually gets stuck when the console is horizontally resting. Placing it vertically may help dislodge it.
4. Wait about 30 minutes.
5. Reconnect all of the cords.
6. Boot into safe mode by holding the power button for 7 to 8 seconds.
7. Cross your fingers. That's really it. The disc should hopefully eject now.

If this has not worked, there is also a way that may resolve this, but it does require a little bit of assembly;

Tear-down Repair (I can upload a guide if needed)

1. Slide down the top cover.
2. Peer down the side of the hard drives, and you should locate a Flathead screw/bolt.
3. Tighten this screw until it has a bit more give than it previously did.
4. Cross your fingers. This is a manual eject button, just in the form of a screw.

A software reinstall would also be a good step to take if this would be a preferred route that you would rather take.