Hello Melissa, I think there is a readme file in the Foxbox package that explains the update procedure. I don't have this at hand right now because I'm on a Mac that doesn't have Foxboxes installed, but I recommend having a look at the readme and trying again.
I'd also check to see if there are any Console messages while
starting. I use foxboxes on all the test systems and there was no
issue with the update, but you must always shut them down before
upgrading the core browser or you may get weird issues like