iPhone 4, out of warranty coverage, won't power on. 1. It has about 60% battery before it dead, but suddenly it became black screen and not responsive (like powered off). 2. Whatever I did, like "holding the power button and home button together for 10-25 sec and then pressing the power button again" etc. it just won't power on, no Apple logo! 3. But I can seen the "emergancy call" screen when I plugged it with my laptop and it just told me "No Service" at the upper left corner (status bar of iPhone 4). 4. iTunes can see it, but only when it was in Recovery mode or DFU mode. 5. I also tried to restore it to factory settings in iTunes, but it always gives me an error with various error codes, like 2001, 2006, etc. I also tried restore it under Windows or Mac, but was out of luck too! 6. Finally I bought a iPhone 4 battery replacement and replaced the old one with the new one, but nothing changed as if it wasn't replaced its original battery. 7. It keeps rebooting at every 10 min or so when It was plugged into my laptop without any operations (pressing any buttons). 8. It can be "powered on" only when it was plugged into a computer. It will IMMEDIATELY be in "dead mode" as long as I disconnect it from the computer (like taking out a battery from an iPhone that is powered on)! 9. Everything worked fine before it dead, I don't know what happened to it! I am so frustrated! Please help! Thank you so much!