After replacing screen using iFixit 6s part display is black

This is my 2nd attempt to replace the screen in my iPhone 6s with an iFixit 6s screen after replacing the battery with an iFixit 6s battery. Although I had done this same job before successfully a couple of years ago, I messed up on this try as I somehow managed to tear the ribbon on one of the video cables. So I ordered a replacement again from iFixit. This time I took care not to make that mistake. When the replacement was completed, the screen did not display anything though the iPhone was working to answer the phone when I called it and swiped where I knew I had to to tell it to answer. And I could tap to hang up the call. But that was all I could do now being able to see anything on the screen. Then last night after days of not working the display suddenly worked but was very dim. So I went to the screen where I could adjust the brightness, which I noticed was at its minimum setting. However, when I attempted to just touch the brightness adjustment to move it up, the screen suddenly went totally black again and I am not able to get it to display at all now.