You need to remove and separate the front panel. There are six screws holding it on. Then disconnect the two ribbon cables and separate the two halves of the front panel. This should reveal the front panel PCB. The SIM card holder is attached to the front panel by a plastic clip.
To remove the " ON " button, you first need to pull off the rotary switch knob around it and then pull off the " ON " button. The rotary switch has a polarising slot moulded into it so it will only fit back in one position.
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