If you cannot get output to your serial console after the firmware update, you might have to clear CMOS settings. This is because your default CMOS settings might have been changed by the update of the BIOS.
To clear CMOS settings, use the following IPMItool commands (in this example, the default username, root, and the default password, changeme, are used):
ipmitool -U root -P changeme -H SP-IP chassis power off ipmitool -U root -P changeme -H SP-IP chassis bootdev disk clear-cmos=yes
Where SP-IP is the IP address of the service processor.
Note - The -P option might not be available on the Windows and Solaris versions of IPMItool. Instead, IPMItool prompts for a password.