As the guts of the phone are now exposed, the square ribbon connector on the bottom rightmost of the mainboard needs to be pried up. This will remove the battery from the circuit.

A few people (Myself Included) have had an issue with this phone where the from notification LED will come on and the screen will stay black. Even if you hold down power for an hour it will still be the same. By fully removing power this way you will solve this problem.

Battery Connector