Smart 451 doesn’t start anymore

Moin, I have a little problem and I hope you can help me. I drive a Smart Fortwo 1.0 84 HP petrol. The vehicle had in the past often displayed the three beams. Then a gearbox reset was made, also worked, but unfortunately only a few weeks. After that we replaced the actuator, went about 6-10 months good. After that we replaced the clutch, because it was already worn out. Now after assembly, three T later, again three beams, I gear reset and it runs again, several weeks went on like this. But now nothing can go on, the vehicle can no longer start, the starter doesn’t turn either, gear position is on N. Already wire harness transmission (with measurements ), brake light switch has been changed, battery new, ABS-SG contacts checked, generally mass connections checked, but unfortunately nothing can be done anymore… Maybe you can give me a hint, what I next time.