Hi,
For Sun you have multiple solutions to get the box down.
A normal one is "init 0" This brings your server safely in the "ok"prompt. By turning the power switch off you've done the right thing and start doing maintenance.
Normaly you choose for init 0 as you are able to find your machine back. The light is colored orange instead of green blinking and you know you have hit the right system. However if you make a mistake it's easier to bring the system back online by typing boot.
A faster way is "init 5" This will not only bring the system to the ok prompt, but immediatly after will shut down power of the system. You have to manualy power up the system again now. You probably understand why I would not choose for this option when you work in a large datacenter.
When having troubles in getting the machine down as it's hanging due to problems in the OS, there is only one beautifull command that always gets your server in the ok prompt :
uadmin 0 2 (or 2 0, can't remember, one just gives an error)
This will kick the server to the ok-prompt, it only syncs data and than leaves the OS behind
Mind that you use this option only in emergencies !!!
Regs David