The first generation PS4's have a known issue of disk ejection failures. Not all do it. Some eject disks mid game. There are many fixes out there. Sony suggests you disconnect your PS4 from a power source and disconnect everything from the device including HDMI etc. Then press and hold the power button, it should double beep. Wait 30 minutes then plug everything back in and see if it works.
Another suggested fix is to remove the top sliding cover, and peering down the side where the hard drive slots in you will see (with a light) a small slotted screw. Turn this screw until it feels tighter, then try your unit.
The screw is the manual eject button.
Software reinstall may fix this issue. (not likely), one other is removing the rubber foot near the eject button as it supposedly creates a friction issue.
Otherwise the last and only fix left is called the Gold button fix. This completely cured my ps4 of disk eject failure. Here is the link to the youtube fix. gold button fix
OK just a quick search on IFIXIT revealed this for your series console. So I hope it helps you out, if it does give the kudos to that poster.
My ps4 wont eject my disc