Mine was rooted, and it bricked it... so no you do not just update it... I just did what I know works.. and that was flash the stock sbf, then apply the update sbf to 311, then vulnerable recovery, and then root again and load a a custom ROM with nandroid back up. You probably don't need to do all that but I only do what I know and it worked for me just fine... I originally tried just going to the 311 update and then vulnerable recovery to root but my apps where force closing on boot that I had installed on the previous version 310.
Hope that helps...