In Solaris 10 (smc gui) select the serial port to be used for service
next click on the action tab, click on properties, under basic tab choose the baud rate, emulation, under the advance tab select...
: If you can get onto the box :
Edit /platform/sun4u/kernel/drv/lom.conf
Change serial security=1 to serial security=0
Log into the LOM, reset the password
Change the serial security back to 1...