If you don't have physical access to the machine, you're stuck ... sit and wait. If you do and all of your services are gracefully stopped, alt+sysrq+(REISUB)
Not the worst thing I've ever done by any means ... but kind of along the same lines. I installed a VPN client on one of our windows servers over remote desktop .. this one machine was kind of in a special place and had "different" firewall rules and could bridge both sides as we needed. Not the right purpose for the machine at all, but pracitcally it was a good fit and would allow us to sneak around a ton of red tape bureaucrat BS.
Well, during the install of that, it temporarily kills the network connection. So I got dropped off... and before the network comes back, there's a box sitting there "restart now / restart later". I had to put in a call to have the guy walk over to it and give it the kick.
production server, during hours.
And then i had to explain to their guy what we were doing, which was sneaky to begin with, and in the wrong environment at the wrong time. He wasn't too happy, but he can't really do anything about it besides complain, so... moving on