Remove the top shell, flip it over, and place next to lower shell

The two halves are connected together via the cooling fan wire. BE GENTLE when separating them

In typical Microsoft fashion, they've made it complicated to remove the fan wire. Not only is it wedged between two transistors it's also adhered with an epoxy like substance.

Using a craft knife, carefully cut through the epoxy to get the cable free. Work slowly and carefully. The thick substance and awkward angles make this a slightly tedious process

Be VERY CAREFUL. You can easily cut the cable here accidentally. If you cut your red/black wires you'll have to patch them. "Slow is smooth, smooth is fast"