After a "successful" replacement of the cracked back housing on my iPhone 3G, it won't start up.

Here are the symptoms:

- when not plugged into any power source it's just a black screen, neither of buttons combination (wake, wake+home, 10sec-60sec...) don't work, it stays black

- when connected to the wall charger, after pressing the wake button, the silver apple shows up for exactly 15 seconds and the screen goes black; again no other combination of buttons have showed any result

- when connected to the USB on a laptop: pushing the wake button the screen just blinks and goes dead with the LCD's pixels "melting down", as if it was forced to shut down.

I've already tried to go through iTunes (start iTunes, connect iPhone while pushing the Home button), it doesn't recognize it.

I tested the battery with a meeter, apparently it's in a "good health", it shows 4.09V though, but I guess it's in a normal range.

I'm a handy dude, having done such kind of surgeries a gazillion times (not on an iPhone though), so I'm aware of any physical damage I could have caused, however I am tempted to believe that this is not a hardware issue (short circuit, bad contacts etc), as the phone shows some signs of life.

The iPhone could not be restored in DFU mode. An unknown error occurred. Error 1601

Has anyone have ever experienced the issue described above (i.e. Apple logo for 15sec and then black screen)?