If you have a Hunter X Core Controller and it doesn’t come on as it should when operating manually the you could have a dodgy switch issue.
Normally to run an individual station you turn the dial anti-clockwise to the ‘run single station’ indicator, then select the station an return the dial to auto-run.
If it doesn’t come on (and you will know its on by the presence of a little sprinkler symbol) then you may need to jiggle the switch a bit and see if you can get it to fire up.
Usually if this is a problem then the dial will not move between the various modes easily. Unfortunately the only solution is to get anew control box as the dial and switches are a complete unit