[Lotus]

if the starter activates and engage the flywheel the “little” cabling stuff works as intended. Their function is more or less digital.

You need to check the big stuff. I know one chap that had a broken cable from the fuse box/battery to the starter motor. Not visible, but intermittently the starter would “clack”, but not spin. Wiggle on the cable and most of the time it worked again. The fix was a new 25mm2 starter cable he build.
I need him to take the insulation of the OEM cable and take pictures.

 

[Lotus]

if it stalls within seconds, you MAP sensor may be defective.
If you have a programmable ECU or an OBD reader, check if the TPS and the MAP sensor all read plausible values. TPS should read 0% and 100% when fully open. MAP should read atmospheric pressure within ignition on, but engine not running and drop to about 300 mbar absolute pressure when idling.
MAP sensor dies if you accidentally swap the black TPS and the blue MAP connector. It then reads a fixed value leading to the car stalling from running overly rich as MAP drops with the engine picking up, but the ECU not removing fuel accordingly.