My home button was acting up, registering double-clicks as single clicks, and single clicks as either no click or double-clicks. iPhone is perfect in any other aspect. So I decided to fix it before I pass it to my Wife after upgrading to 4S.
I was able to follow the step-by-step instructions on iFixit without any trouble, until I could not reconnect the digitizer cable during the reassembling process. Turns out the cable was pinched when I assembled the screen. So I reverse the steps and straightened out the pinch. After the battery is reconnect, I tried to turn on the phone and only half the screen is working, the right-half of the screen is just black. I tried to disconnect and reconnect the LCD connector multiple times to no avail. So, I took the iphone apart again and see if the LCD cable is pinched again somewhere. Did not find anything and went ahead and put the phone back together. By now I could already memorize all the steps without having to follow the step-by-step guides on iFixit. This time, the entire screen turned black, nothing worked. Ha! I guess I somehow damaged the LCD cable when pulling it through the slot of the main body. Ok, bottom line is, I broke my phone and rendered it entirely unusable.
I had no choice but went to the Apple store and paid $149+tax for a replacement iPhone 4. I took a chance and trusted my own fine-motor skills. Turns out, I am getting old.
I think iFixit should put a note on the step-by-step guide to warn people to be extra-careful with the LCD cable. Looks like the way it is connected to the LCD module is quite fragile and can be easily damaged. I hope other readers of iFixtit can avoid my costly mistake.