Screen doesn't work a couple of days after repair

Hi guys,

I repaired my iPhone 4S screen last Monday, using iFixit tools and parts. The repair went perfectly, following the instructions here. The phone worked perfectly after the repair as well. Now today, out of the blue, the screen only showed a blurry grey, or, depending on where I applied pressure, displayed the screen as it should be. Everything else worked, messages, mails etc. were received, the phone vibrated, the touch screen worked. So I figured it was maybe a cable on the logic board that I failed to put in correctly, so I opened the phone again and checked all the connections. Upon turning the phone on again, the screen is now only black, and no pressure will display anything else than the 'light black' of an illuminated screen.

Did anyone already encounter such a problem? Is it possible that I broke something during my repair that only just now showed?

I guess my next step would be to just do it all over again...

I'm very grateful for every comment!