W169 A150 start and die

[alessioblaupunkt]

Mercedes W169 A150 petrol
crank always
The first, second and third start the engine shut off in 1 second.
Start and stay at idle at 4th attempt. Might shut off a few seconds later or stay at idle.

This is not an original car:
This car is fully controlled by hand, no pedals on this car.

The first scan is full of errors related to battery voltage low,
tons of no stop signal, tons of no can communication (has no pedal)

Once erased all errors there are no fault even if car does not start instantly.

A few attempt later I can see if I accelerate the engine goes better,
but owner reported he tried to accelerate but engine rpm slow down.

I've tested for current drawn and at the moment there are no abnormal current drawn,
had a look to front doors wiring but wires are intact, also for trunk wiring.

Changed battery, put an 62Ah 540A lead acid as the previous was a bit low but I'll test
better tomorrow.
Alternator voltage is 13.07V at idle and 14.21V at 2000 rpm.

Had no time to look at idle motor, spark plugs, relay ect.
Think I'll have no time even in the next days.

Please suggest something.

[Meat-Head]

Look on live data and see what throttle % is

how long customer had car

how long faulty

tell customers to grow legs and buy different car

battery fault codes with new battery?