The power button can be accessed by removing the back of the phone. From there it can be pulled out and replaced. Check out the Troubleshooting Guide.

The microphone can be accessed from the motherboard. From there, you can replace it. Check out the Troubleshooting Guide for more help.

Using a paperclip, insert the end of the paperclip into the hole at the top of the phone to press the SIM card down. The SIM card and SIM card tray should pop out after you press it. From there, you can insert a new SIM card. Check out the Troubleshooting Guide for more help.