I decided to get the latest update (the one that appeared on April, I believe) through the PC Companion, which worked, but then I could not root. Then I followed the instructions here: http://androidforums.com/play-all-things-root/532500-solved-cant-root-r800at.html, though I skipped Step 5 (the re-upgrade step). Now I can root again, but the Home Button does not work. How can I recover its functionality? If anyone needs more details about my phone, please ask.