406 does not start; 2 KfZ masters face puzzles

One master works at Peugeot, the other one has a free workshop. So: from +4 degrees and colder he no longer jumps on his own, even though the starter turns and the battery is strong. The following parts new: OT-Geber, temperature sensor, idle control. According to both experts after the diagnosis it is clear: there is no petrol from behind or there is no ignition spark, so “Startpilot” did nothing. Then he has to “catch” himself for a moment and then stays on. After that, if he goes out, he jumps again with his own strength. But as soon as he has stood for a few hours, nothing happens again. Both it is completely inexplicable why he still starts by towing would be great if one of you still has a ignite idea Thank you