After I dropped my PS4, discs would no longer spin after being inserted and I would eventually get an unrecognized disc message. After watching many videos on YouTube and verifying that the connecting rod and rollers were intact, and no other obvious issues were present, I realized that the little white disc ended up coming out of the carrier. Simply placing it back in the carrier fixed the problem. This may have been a fluke situation for me but I figured it was worth posting since I was unable to find any videos that describe this potential problem.

If you need to understand how to disassemble a PS4, there are many videos that can be found here on YouTube that will show you how. It is not difficult if you are not afraid to do this sort of thing.