2000 GMC Jimmy just won't start....

I have a 2000 Jimmy and it just won't start. When I turn the key, it won't crank, just shows a SERVICE ENGINE SOON LIGHT. I had this problem before and the problem was a bad starter relay. I've replaced the relay, again, but it didn't solve the problem. The vehicle started up fine and ran great all day, until this afternoon when I tried to restart it. Battery is good, changed the plugs this past fall, starter was replaced a year ago and I checked all the fuses related to IGN, all are ok. I just don't know what the problem can be. I'm new to the forum and tried to search for a solution with no avail. Any suggestion on a solution is really appreciated.

Welcome to AF, does the security lite stay on? Do you have 12v to the starter solenoid when the ign is in the start position?

No security light. When I turn the IGN, only light on would be the SES light. I don't know if I'm getting 12v to the starter, how would I check it? I just tried to start it again, and it just fired up, like nothing was wrong. I'm gonna take it to a shop & let them run a diagnostics on it to see what went wrong. I'll post the result here for anyone that has the same issues.

The starter had a bad spot on it and need to be replaced.