Bumping this thread to notify you all of a fix for the eject problem.
After cleaning out the PS4 and changing the thermal paste, some of us now had eject problems where the eject button (capacitive one) would function wrong or not work at all. Most of us just resorted to using the eject via the home screen because of this.
So yesterday I opened my PS4 to clean the dust out, the last time I opened it was when I did my thermal paste change and since then my eject button wouldn't function properly.
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DISCLAIMER: BEFORE PROCEEDING MAKE SURE YOU KNOW WHAT YOU ARE DOING, I AM NOT RESPONSIBLE IF YOU MESS UP YOUR PS4 EVEN MORE***
The only issue that can occur from attempting this is that the two contacts are still not touching each other, this can lead to the eject button not beeping or your PS4 not accepting discs. Just try again and bend the metal contact again in a way that it will touch the gold contact on the board to fix this
With that out of the way on to the fix...
Just a reminder make sure you are working on a hard floor not on a carpet, and that your PS4 is shutdown and unplugged. Turns out the way the eject button works is that there is a metal contact on the bottom housing of the PS4 that is supposed to touch a gold contact on the board. I figured when I was re-assembling my PS4 I somehow managed to bend that metal contact so it was not touching the gold contact properly which led to the eject problem. I ended up bending the metal contact in a way that made it touch the gold contact and then gently placed the bottom housing back on. Below are pictures of the gold contact and the metal contact that need to be touching in order for your eject button to work. I also made a diagram on how the metal contact was bent in order to fix the problem in my case, just do your best in order to make them both touch each other. It can be hard to guess since the housing needs to be attached so you won't actually know if they are touching each other or not without testing the PS4. Also lastly make sure there is no dust so do a thorough clean since the dust can interfere with the button as well.
My eject button is working fine now and beeping normally as well. Sony could of prevented this if they just used physical buttons instead of the capacitive ones on the launch PS4s, which is what they ended up doing for the new models. I hope this helps out others who have been facing this issue.
*Most tutorials and guides do no mention this, but be extremely careful when putting back the bottom housing or you might end up accidentally bending this metal contact and this will most definitely lead to eject issues*