My Beta alp (2000) sits in the garage since it stopped at the Carsington water halt in 2017 and did not run again
Alp experts tell me "It could be your electronic box, we cant test it you will have to fit a new one (£250) to see , of course it may be something else"
Its a very competent machine it got me a silver for the first time in many years it has a illuminated tesco salad box to hold my rote card-very swish
But it lacks some charisma and that's what I need on a wet night with every signpost saying "South Moulton 8 miles"
I will either have to mend it, sell it or wait another 7 years until its VMCC eligible :-)
You might not be able to check out the ECU directly, but have you eliminated all the circuitry that provides inputs to the ECU and to the circuitry that receives the outputs of the ECU? If you haven’t, take a look at the wiring diagram in the Beta Owner’s Manual. If you haven’t got one, you can download a copy from the Beta website.
You’re pretty clued up I know, so I’m assuming that you’ve checked the 10 A fuse and connections to the coil

. First off, disconnect the wiring connector to the ECU (central electron in Italian) to get access to the pins to and from the ECU, then get out the multimeter.
First thing to check is the 12 V supply to the ECU; this comes from the ignition switch, through the side-stand relay and the kill switch to the ECU. It should be the white/yellow wire at the ECU connector. You should be seeing 12 V with the ignition switch on.
The second thing to check is the connection to ground, which is the black wire.
The third areas to look at are the pins from the pick-up (yellow/black wire and white/red wire) and the pin to the coil (bobine) (black/red wire). See if you have an acceptable resistance reading.
Fourth, to check the circuitry from the generator (white/brown wire). See if you have an acceptable resistance reading. You might even see a voltage output if someone spins the engine.
There could be some errors in the above and it’s based on the wiring diagram for a 2006 Beta alp 200, but you can get the gist of what can be done

.
If the problem is not found after these checks, then might be worth a punt at a new ECU

.