iPhone 5 screen unresponsive and dimming

Hi,

Not too long ago, I dropped my iPhone 5 and the screen was completely cracked. I decided to repair my iPhone myself. (I have a decent amount of experience in reparing iPhones)

I installed a new screen without any difficulties. Unfortunately, the touchscreen started acting strange. The phone display dims time to time (once in ~5 mins, very random) and becomes unresponsive/lives a life of its own and randomly clicks apps, types etcetera.

I have tried a restore 3 times now, but this wasn't the solution. I've also tried an other (high quality) working screen, but the problem persists.

I did find out that slamming the upper-left corner, on the rear, turns the brightness of the screen back to normal but it will stay unresponsive untill I lock and unlock my iPhone.

Yesterday, I opened my iPhone to see if I could find the part that was causing these issues. I found out that when the screen dims and becomes unresponsive, I was able to recover the phone's brightness by pressing on the upperleft corner on the metal shield. After I lock the phone and unlock it, the responsiveness returns.

Today, I found out that when the screen dims, and it loses it's responsiveness, I am able to recover it's brightness and responsiveness by simply applying force on the rear of the iPhone. (just pressing next to the apple logo: http://imgur.com/a/DuaQ0)

Does anyone have any idea what I could do to fix this phone? Buying a new one isn't an option, as it is my (recently discovered) hobby to fix phones. I'm trying to find solutions to multiple issues.

In addition to all above:

- I checked the connectors that could've caused these issues (touch connector/lcd connector), but they both look in great condition (no dust, no signs of damage or loose connection.

- I cleaned the connectors just to be sure, without any luck.

Looking forward to (possible) suggestions.

Thanks in advance,

Nabil