Why does my camon 15 lower screen gets overheated

@geez81298 the only thing that is behind that screen on the lover part is the charging board. I doubt if would get so hot as to shut down your screen. This sounds more like a display error.It would have other issues first. I would replace the LCD and then re-evaluate.

Since iFixit does not yet have a guide for this, use something like this video.

Replacement screens are readily available. Just select a vendor within your geographical region and make sure it is for your exact version.

While you work on your phone, take lots of pictures. Once you are done with it, take those pictures and create a guide for iFixit. That will help the next person that has the same problem as you do. It's easy and fun to create these guides. https://ifixit.com/Guide/new The iFixit community will appreciate this.