From my personal experience this happens from the camera flex not be connected 100% but it really could be from really any connector or flex being damaged, I mean did you try to flip up any of those connectors while you were in there? I've done it once and I obviously ended up in the same position as you from it. I'd just go back in and unplug and replug your connections and make sure they're latched on by pressing on them a bit once you're sure they're in correctly. On the bright side you were just working on the bottom half and it'll make easier to double check everything. Please let us know what happens!