No crank no start

Hope all is well , mid level mechanic here looking at a 2010 Ford focus that will only start sometimes , I checked fuses and relays even though I doubted that from the beginning because the car does start sometimes but I’ve learned my lessons about ruling things out. So fuses and relays are fine , battery is good and checked for power going to the ignition switch all the wires to the switch are looking good getting good voltage. Customer said he had the switch replaced a little while back but recently the car only starts after spending a while trying to start it once it’s started it drives fine no problem I even got it to turn over once during my diag but that was it, I took apart the key cylinder and tried turning it over with my screwdriver as well and it still would not start nor crank, finally I hooked my starter switch to the starter to jump it and the starter began to crank but wouldn’t turnover the engine, while attempting to crank from the ignition it will not even crank . At this point I’m going with faulty starter but would like some insight or confirmation on anything else I should check before replacing it .. also I tried starting the car in different gear selections to rule out the neutral safety switch… please help

 

What is the the anti-theft lamp doing when it won't start?

When it will not start, try the second key. Keys can sometimes lose their coding.

 

Never payed attention to that I’ll take a look I will say it is a after market key it’s not a original key it’s the only key the customer has my first guess was maybe it’s worn? When inspecting the key cylinder but it does have resistance when inserting and removing key sounds like it’s clicking in all the spots but I’m not a lock smith so I could be wrong

 

The right key is coded to the vehicle. Another key may operate the tumbler, but if not programmed to the individual vehicle , the anti theft system will not recognize it and prevent the starter from operating or fuel injectors from working