Glass replacement - Touch working but blank screen

Hi All,

I had a galaxy S4 with a broken glass (but everything else ok) that I don't use anymore but I thought I would repair it so that kids could use it for games.

I followed directions here Samsung Galaxy S4 Cracked Front Glass Replacement

I removed the broken glass without too much difficulty with time using a kind of heat gun that I had at work.

I tried to clean the digitized with a humid cloth because I didn't have alcohol but as expected it didn't clean anything.

After 30 min I thought I would try to turn the phone on, so I put the battery and used the power button, unfortunately I got a flash of a hozirontal green lines on the right 1/8th of the screen, and then the lcd stayed black. Otherwise the phone works well, touch still works, I was able to check that using 'adb screenrecord ...'

Here's a video of what happens https://www.youtube.com/watch?v=-BacbRvT...

Weirdly the video caught only the top part of the green lines but they show up from the top to the bottom

I checked the LCD flex which seems well connected. I wouldn't get touch if it wasn't?

I can reproduce the green lines on poweron if I have not powered on the phone for a while (15 minutes). Otherwise no flash.

What do you think? Did I damage the LCD+Digitizer?

Is it not unusual to damage the LCD without damaging the touch?

Could this be due to overheating?

Thanks in advance

Pierre