You are booting a Sun LX50 which has a Service partition and Solaris 10 OS on x86 is installed. Pressing the F4 function key to boot the Service partition, when given the option, causes the screen to go blank. The system then fails to boot the Service partition.
Workaround: Do not press the F4 key when the BIOS Bootup Screen is displayed. After a time-out period, the Current Disk Partition Information screen is displayed. Select the number in the Part# column that corresponds to type=DIAGNOSTIC. Press the Return key. The system boots the Service partition.