LCD screen not working, camera in good condition, but bought second ha

Hi,

Here’s a video that shows how to replace the LCD display for the camera.

Here’s the ifixit Sony Cyber-shot DSC-HX300 LCD Screen Replacement guide which may also help as the two cameras are nearly the same

Can’t find a supplier for a HX400V LCD screen but there are plenty available online for a HX400 LCD display - example only. Perhaps the LCD display might be the same or you could try getting one for a HX300

Just search for Sony Cyber-shot DSC-HX400V lcd screen (or HX300 LCD screen) to find suppliers that suit you.

Hopefully thisis of some help.