Recovery Mode is not somewhere I go every day, but I did wipe the Cache Partition a few days ago and as I recall, from the No Command stage, you use the Volume button until you get the Recovery option, enter Recovery by pressing the Power button, then navigate the options that appear by using the Volume button....in your case, to factory reset....and then pressing the Power button when you've highlighted what you want to do.
Edit, Jan 2017: I don't know what I was gabbling about there. From No Command, you press and hold Power, then press Volume Up once.
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