Update not working

[r4nd0m1z]

I am currently running v15.5.4, but 15.5.9 is the current version. When I click on the update button, I see the update running in the terminal screen but when it restarts it's still running v15.5.4 as indicated in the terminal window. If I try to run the update script manually (./scripts/update.sh), I get "permission denied." If I try sudo ./scripts/update.sh, I get command not found. Any idea why it's not updating?