What is wrong with my printer?

Hi
I have a Anycubic i3 mega S which is giving me weird problems. For example it was makeing weird noises and mixing different files during print, all of a sudden; Super wierd.
I thought the SD was corrupted so I started using a new one. I've printed some square tiles for d&d and had no problemens but noticed the square were not perfeclty square so I decided to print a Calibration cube with Cura calibration plugins.
Again crazy noises and printer doing crazy things. Tryed to download a calibration cube and print it; same problems. Tryed to change SD; still the same.
I thought "that's it my printer is done."


Then I tryed to print again the square tile and it's printing it without any problems....


What is wrong with my printer?
Here is a video of the problem. Skip to minute 1 if you want to see it.
https://youtu.be/4D5BNj9CB1I


Hope you can help

Hi Avensis. It looks like the problem is about faulty SD card/not properly removing an external dirver...Most probably the second one, yet I've been removing the SD card in the same way for 3 years and now all of a sudden it gives me problem and I have to do everything with the outmost care.

Have you tried printing directly from a USB connection? Take the SD card out of the equation?