You need to start the server with minimal services running so that you can go through each milestone manually to troubleshoot the issue

Your SPARC server will not boot into multi user-server milestones and you need to troubleshoot to
out why. You need to start the server with minimal services running so that you can go through
each milestone manually to troubleshoot the issue.
Select the option that boots the server with the fewest services running.

A.
boot -s

B.
boot milestone none

C.
boot -m milestone=single-user

D.
boot -m milestone=none

E.
boot -m none

Explanation:
The command boot -m milestone=none is useful in repairing a system that have
problems booting early.
Boot Troubleshooting:
To step through the SMF portion of the boot process, start with:
boot -m milestone=none
Then step through the milestones for the different boot levels:
svcadm milestone svc:/milestone/single-user:default

svcadm milestone svc:/milestone/multi-user:default
svcadm milestone svc:/milestone/multi-user-server:default