"ps4 is not taking in disc but plays them"に関する回答This is very common with those. It’s most likely not the motor and sensor board. The circuit board on the optical drive has tiny fuses on it. You need to use a multimeter and test for a blown fuse. You can either replace the fuse or short it out with a drop of solder if you feel lucky. These are labeled starting with an “F” and then a number.
"laptop turns on, screen black, won't turn off"に関する回答Have you tried an external monitor? One of the first things that your computer will do is check the RAM. If you have more than one stick try it with each one separately. I would take it apart and unplug components from the motherboard until it works.