Insert and gently push the SIM card ejector tool (or an unfolded paperclip) into the small hole on the left side of the phone's top edge.
Press gently to eject the SIM tray
Remove the SIM card tray from the device.
To reinsert the SIM card tray, orient the SIM card with the gold contacts facing up and the notch to the bottom right. Reinsert the SIM card by pressing the card gently into the SIM tray slot.
Disconnect the flex cable using the flat end of a spudger or a pair of tweezers.
Remove the phone's back cover.
To reconnect the flex cable during reassembly, angle the back cover until the flex cable lines up over its socket. Use the flat end of a spudger to snap the cable in place by gently pressing straight down.
Place a heat shield over the other parts of the motherboard to avoid overheating.
Heat the affected area with a heat gun to reflow the solder.
Reflowing heats up all the soldering joints in an area so they become liquid enough to reinforce the bonds. This allows electricity to flow through the bond without unexpected resistance.