Ender 3 doesn’t turn on

I’ve got an Ender 3 for some time and the LCD was kind of “blurring” in some points. I decided then to update the firmware and the LCD got even worse, in a way it was impossible to understand anything that was written. I tried many firmwares and one older worked. But then another problem happened: one day the printer was hearing to print and when I was about to start moving the motors it turned off and never turned on again. I checked the fuse and it has current, but nothing turns on, not even the fans. What should I do?

Did you check if the controller board has the 24V it requires? What did you check about the fuse, just that it was not blown?
If it does not turn on probably either a broken power supply, broken cable or broken board.

Well, I didnt, because it was working up until now hahaha

And about the fuse, I used the multimeter to check if there was current.

Using the multimeter check the PSU is outputting 24v and then check it board side.

That will rule out the PSU and the cable.

Depending on the board it will also have a fuse check that is not blown

As it started with the screen it could be that the cable is shorted going to it causing your issues.

Using the multimeter again you can check for continuity across the wires

Have you checked the voltage switch? If it has the correct setting then maybe loose wiring, broken PSU, or motherboard could be causing the problem.
You can also check out my article on this: Ender 3 not turning on