Volvo 780/D13 starter problem

I stopped the motor at fuel island and won't restart , the starter doesn't engage; I knocked it with a hammer, sometimes woks in cold weather, but nothing; i have power 12.9v, ; I turned the ignition on ,crowled under and truck with a wire bypass ignition and it started fine;I'm on a hot load moving , can't stop it like Keanu Reves in "Speed" all Volvo shops are closed on my route ,what could be the problem? I checked fuses, but I don't know how to check the ignition relay ; the starter is less than 1 year old.

 

They checked the wires ,but the solenoid was bad ,i replaced the whole starter they don't have the solenoid only , @ Volvo, Laredo ,TX ; took them a day to figure out; stay away from this Volvo shop; are working like pregnant ladies 8AM to 6:30Pm with 2 hours lunch break.