stuck at black screen and DFU and recognised by iTunes, but waiting

Hi everyone,

I'm new to iFix it. So this is the challenge:

iPhone 5 had a headache problem as it was randomly rebooting. I saw that mostly the display just dies and than after couple of seconds the phone reboots.

First I thought that it was due to the battery and tried 2 new ones and one battery from another working iPhone 5. Nothing helped. Than I changed the dock connector and this also didn't help. Then I disassambled the whole iPhone and I have connected the LCD with the main board and the dock connector. Well, the iPhone still randomly rebooted. So I did some research and couldn't find anything that could help me exept that it could be an IC issue (most probably U2 IC = Charging component). There was an example with and iPhone 4s. The example explained that I gotta bake the phone at 196 degrees Celsius for 7minutes, which I did.

Now the LCD is black, most probably in DFU mode and iTunes recognises the phone. I clicked to restore and now it shows: waiting for iPhone. Unfortunately, i'm stuck here and I did all the combination to get out of DFU or so...but nothing!!!

Please help me to diagnose the issue and fix this.

Many thanks in advance for your replies.

PS. I suppose that I will have do some soldering.