You have to press volume up and the power button when entering RCM with a jig of some sort. Your screenshot even says in Step 1 that you need to short the pins somehow. See my previous post. You need to use one of the methods in the thread I linked to in order to enter RCM. The paperclip method is my recommended way of doing it if you don't want to order a jig online. Once you use the paperclip to enter RCM, you can install AutoRCM so you don't need to use the paperclip ever again.