Place a soft cotton cloth down on the table. Take a paper clip and straighten it out. Now insert the paper clip in the small hole at the top of your iPhone 2G and push the paper clip inside the hole till the end of the SIM jacket begins to pop out of the phone. Now pull out the SIM tray and place it on the cloth.
Now put your iPhone 2G face down on the cloth. Arrange a utility knife and push in the tabs inside the black connector to remove the connector from the iPhone 2G case. Insert the knife at the bottom of the iPhone 2G between the antenna cover and the dock connector. Pull the Antenna cover out.
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This next part is a bit tricky. Insert the knife slowly in the gap between the antenna cover and front bezel. Slide the knife till you reach the edge of the bezel; continue with this till you reach the end of the metal casing. Then take out the utility knife. Use a screw driver to remove the three screws at the bottom of the iPhone 2G. After unscrewing, remove the rear panel of your iPhone 2G. You will see a small square hole, insert a toothpick in the square hole and manoeuvre it till you dislodge the inner rear panel. Repeat this process for the bottom side of the iPhone as well.
Peel off the orange coloured tape from the white antenna cable to disconnect it. Use a knife to cut the connection between the antenna and the phone circuit board. After that remove the camera module from the iPhone. Now insert the Knife in between the phone and battery and remove the battery. Now use a screw driver to unscrew the three screws attaching the front panel to the phone. Similarly rotate the phone and repeat the same steps.
Congratulations you have successfully opened your iPhone 2G.