Your Bluray drive is failing. You can try cleaning the laser but you might need to replace other components depending on the issue (disc not pulling in=one of the motors, disc not spinning=drive motor, disc spins but can't be read=problems with the laser)
Put everything back onto the sd, the 3ds won't work without it! If that doesn't work, get a flashcart (such as the r4i) and follow the steps on https://3ds.guide/ntrboot to reinstall CFW and get everything back to normal. Let me know if you need more help, I've done it about 5 times and know how it works.
Could be that there is dirt inside the buttons (the actual buttons that control the circuit, not the plastic outer ones) or that they are bent in some way. Try to get Nintendo to fix it because there are almost no spare parts available yet.