I'm having a similar problem where I think I messed something with this step and now my computer is REALLY slow and I cant get any wifi. Heres my story.
I am going to put a SSD in place of my HDD so I also took the optical drive out of my mac to reduce the weight. If this matters I also changed the fan because that was broken. I'm wondering what the problem could be. One thing im confused by in the guide was step 5. Am I supposed to remove that connector? If so how do I do that? I may have wiggled that a little trying to take it out.
My computer will boot up very slowly but the mouse and keystrokles lag by about 4-5 seconds. The computer won't connect to wifi. The battery symbol has an "x" inside the battery so I keep in plugged in. It also has my apps in the dock and my name in the upper right hand corner.
Any ideas what is wrong? If something is wrong how do I clone my old data onto my new hard drive? If you have any questions about my situation ill gladly answer them.