Black screen issue and lost SMD parts.

I have bought a second hand iPhone 4 with a problem. But it was a big mistake because seller hadn't said the truth. I had supposed it has got a simple problem. Actually he had told so. He had said 'iphone was stuck apple logo and I wouldn't try out to fix because I haven't waste time. When I looked the logicboard, all of emi shields were removed. I had understand he tried to fix it clumsily. Also there wasn't apple logo when I press power button. It was only black screen. When I contact the computer, the computer recognize the iphone. When I contact itunes firstly says 'itunes found an iphone in recovery mode' and then it says 'it must be restore'. But it was stuck when it was restoring. I have tryed plenty of times. One day I noticed lost part upon the headphone jack connector. I transplanted the lost part from my donor logicboard. But I failured again. After almost one week, when I press power button, the apple logo appeared and then it turned white screen. I started to fix again. Black screen again. And today, I noticed a lost part near the charger connector. I would transplant it from my donor logicboard. But I lost it because it very small. Now, I wonder what functions are those smd parts have. And where are identical parts on the logicboard. Is there smd chart for iphone 4? Apologize for my weak english. I really maked an effort to write. Thank you for your helps.