Success! The brightness is back to normal now. The solution was to use sudo /etc/acpi/sonybright.sh down and sudo /etc/acpi/sonybright.sh up
Reference: https://bugs.launchpad.net/ubuntu/+source/linux- source-2.6.22/+bug/152095 -- screen appears dark even at the BIOS level https://bugs.launchpad.net/bugs/231359 You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
