just adding to the list, mine also died 6 months ago, ATT variant. Very carefully used. Battery is good (checked with meter). No issues with charge port. Just dead. Really disappointing.
Ribbon #3 slides in from the TOP (the black end), but the lock is on the BOTTOM (the white end).
On the BOTTOM, you can open the lock easily by lifting the bottom edge upward... it flips straight up.
now I understand.. the pic is of the 3GS, but this is correct for the 3G. Hard to visualize, but the lock is opposite of where the ribbon went in. Doh.