Why is my screen at the top is not working?

@dungalewong you are not telling us how (no image, bad image, touch not working etc.) it is not working. Details really matter when it comes to repair. Anyhow, if the screen is not working properly , you will have to start off by replacing it. Since iFixit does not yet have a specific guide for this, use something like this guide It is written in Spanish, use a browser that will do the translation for you (if needed). Replacement screens are readily available at many online stores.

Should a new screen not fix this the issue will be related to either a bad connector or a failed component on the main board.

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 a device with the same issues as you do. It's easy and fun to create these guides. https://ifixit.com/Guide/new The iFixit community will appreciate this.

Repair is War on Entropy!