Anther important omission is the data connection to the card reader, which needs to be disconnected in Step 11 (this is one of two connections between the motherboard and the bottom of the case).

Also, to replace the motherboard you must remove the CPU and RAM from the motherboard, so they can be connected to the new one. This guide does not cover that.

This guide could really use an explanation of how to disconnect the different types of cables from the motherboard. In particular, the descriptions for steps 16 and 17 are completely inadequate to me.