Ask for help: Does anyone know this problem?

Hello dear elk driver So, now it’s time: After a good 2 years with my S60 2.0T, MJ 04 and nearly 40’000 km I had my first breakdown: The car didn’t start in the evening and I was stuck in the parking of my company! The problem turned out as follows: The Fzg. let itself open without any problems with the remote control and everything looked really good. But when I wanted to start the engine and the starter operated: nothing happened! No error message, no whirring of the starter: nothing! So I tried among other things again to close and reopen the car with an additional battery? And look: Wrumm, the car started again without a problem. Anyway, he tested the battery voltage and that was ok! So I drove quite normally after the car in intention to have nothing to start the car with an additional battery! And look: Wrumm, then the car started again without a problem. In any case, he tested the battery voltage and that was ok!