Hi,
I did exactly the same as you did on my Galaxy SIII. And also couldn't get play store to open to reload FB. Go to your settings menu, scroll down to "applications", scroll sideways to "all" then scroll down to "Download manager". Select it and when the screen comes up press on "Enable". Once this is done, you should be able to load FB again. If the FB build message is still showing, go to the apps menu, select "downloads" then scroll sideways to "other downloads". Click the box and press the garbage can to delete. Then restart your phone. The problem should be solved. Good luck !! xx