How can I safely shut down without a monitor?

Booted up about an hour ago for the first time. Tried 4 different monitors. Miner recognized one of them long enough for me to enter the login password, but then it stopped recognizing the monitor after that. The guide says not to shut down until the green light at the bottom of the miner goes off. I have no way to shut down without a monitor. Wondering if I'm going to ruin this thing if I just turn off the power supply.