Brew button depresses but does not activate machine.

Got a Keurig from a thrift store. They turned it on and showed me that all of its features (short of actually brewing something) were functional. I brought it home, cleaned it out, and set it up. I can get all the way to choosing the cup size (4oz - 12oz) but when I press the brew button, which seems to go all the way down and “click”, nothing happens. This is the case whether it has a pod present or simply dispensing hot water. Is there a way to check the button for possible debris or damage? Replace it? Remove it entirely and jury rig it somehow? Or would the issue be deeper such as replacing a board?