No video, no sound and no touch response after screen replacement

After replacing the screen of a working iPhone 4s with broken glass, taking care to disassemble and reassemble the smartphone with the greatest attention, the device has no video, no sound and no touchscreen response. By connecting to a PC, I can note that the device "works": the operating system starts up without problems. Watching mainboard under a microscope I noticed an unsoldered pin on the LCD connector, as shown in the video:

https://www.youtube.com/watch?v=Tn2mUIEI...

Someone is the same thing happened ?? I'm in trouble and I would kindly need your advice on how to proceed. I'm provided with sealing station and motherboard's spare parts, but do not know which components are damaged. Please help! Thanks in advance, elnano.