Depending on what spindle drive you have, there is either LED's on the sp drive or a 4 digit 7 segment display that will display the status. What is the "?" light mean, or is this a 'mystery' light, is it the spindle start light on the operator panel?
If the drive looks like it has been activated but the spindle does'nt turn, Check the brushes if it is a DC spindle.
Al.
CNC, Mechatronics Integration and Custom Machine Design
“Logic will get you from A to B. Imagination will take you everywhere.”
Albert E.