Yes, there are only 2 buttons. But, if you keep pressing the "-" or "down arrow", brightness will decrease all the way down to 0 (Zero) and the start increasing one increment at a time back towards 100.
Problem Solved. . .
This is actually a pretty good 27" monitor for around $200.
The manual on the S27C230B says I can adjust the brightness, but once it goes down, there is no "Up" button. I chatted with Samsung support, and they told me to use the + and - buttons. Umm, there are no + and - buttons. So I am told that once I turned the brightness down, there is no way to turn it back up. I did a reset to "factory settings" but the brightness didn't budge. What is the trick to turn the brightness back up?