Can't RDP the box or get to it any other way?
I discovered a little trick about a year and a half ago, and it has been saving my life, and those of my colleagues ever since. I just actually had to use it, which reminded me that I ought to post it.
$server = gwmi win32_operatingsystem -computer USSERVER1
Performing this will provide you with some output. As long as it comes back with an output of zero, you are good to go. I believe the target server doesn't even need powershell installed; just the one you are using to reboot it.