Hello,

I have an iPhone 2G that doesn't power on.
Just the black screen.

Nothing when I press and hold power.
Nothing when I press and hold power + home.
Nothing when I connect it to a dock/charger.

BUT

When the battery is removed and I plug the phone in the charger it shows the white apple logo!
So I know it is not completely dead.

I have replaced the battery and I still have the same problem.
Should it be a bad replacement battery?
Or is maybe the dock connector broken? (I doubt that because without battery it wants to start)

I hope this is enough info and I sure hope there is someone able to help me!