Update 2.55 dropped today. Now it constantly ejects discs, and every 30 seconds tries to eject a disc again even though there's no disc.

Wait a day or two and google it.  I'm sure you aren't the only one.

Can't remember exactly, but I think it is under or on the side of where the hdd cover is located, but there is a screw that you can turn (need a smaller flathead). Put your disc in a bit and turn it, or just turn it and see if that fixes it.

Or unplug your system and hold the power button for a good minute, or until it completely stops beeping, then try to load a disc.

Yep. Mine ejected disks from time to time. Simple fix.
Actually the temperature in my room was what determined if it was going to eject the disk or not. If my room was hot the disks would eject. Once I turned my AC on and the room cooled down it stopped. I would turn the AC off if the temp dropped and the disks would eject again. I eventually did a google search and solved the problem.