2/35 is the starter relay. The guys in Denver may have got it wrong, have you tried a different starter relay?

On the 8 cylinder power and ground to the starter relay coil is supplied by the ECM.
Check for continuity between the ECM and starter relay on both wires.
Did you clean the ECM ...

As the title states. My XC90 ran great all winter in the Rocky Mountains. Was road tripping home and stopped to see a friend in Denver. Stay the night and next morning no crank no start. All electronics work fine. Never had an issue like that before. Towed to the dealership where they diagnosed it ...