Both the power and home buttons not working after screen replacement?

I replaced the screen + LCD/digitizer on my white iPhone 5, and after both the power and home buttons aren't working! I checked all the connections and the only thing I can think of is I wanted to disconnect the battery just to be safe and I tried to remove it for some reason after I disconnected it. I broke off that little plastic tab that says "Authorized Service Provider Only". I then tried to pry off the battery in the same spot and I might have damaged the thin skinny black ribbon cable that runs alongside the right side of the battery. Thanks, I need help.

Vince