My Screen Backlight won't turn on after a hinge repair

Hi @enricogabr24424

Turn on the laptop and try shining a flashlight at an angle close to the laptop's screen and check if you can see any images on the screen at all.

They will be very faint if they are there so trying this in a darkened room may help.

If there are no images to be seen, try connecting an external monitor (TV?) to the laptop's HDMI port and check if the laptop displays on it OK. Don't forget to operate the appropriate function keys to switch the display to the external monitor.

If there is no display on the external monitor then there's a problem on the motherboard that needs to checked further. For this you will need the motherboard schematics. (see below)

If there are images to be seen then there's a backlight problem with the laptop screen.

Since it seems that you didn't disconnect the battery from the motherboard first thing before doing anything else inside the laptop, (is this correct?) you may have accidentally blown the backlight fuse on the motherboard.

I can't find the schematic for the motherboard (is it an NM-E341, printed on board?), I don't know which fuse it is or where it's located on the board.

There's this video for another IdeaPad 3 15 model that may or may not help, as it shows where the fuse is located. Worth a look perhaps if the laptop is open.

If you want to be sure, there's this website that has a download for the NM-E341 boardview (tvw.zip file) and schematic (Rev.01 pdf) files but you have to join to download from them, (and possibly pay??, I don't know as I didn't try).