2013 Mazda 6 Skyactiv – Engine starts, but NO charging. Two alternators replaced. Car sat in the driveway for a month.

2013 Mazda 6 Skyactiv (UK), approx. 89k miles

My car has been sitting in my driveway for a month and I’m completely stuck.

Important: the engine starts and runs, but the battery is not charging.

Symptoms while driving:

•“Charging system malfunction – Engine could stop unexpectedly”

•Red triangle and multiple warning lights

•Power steering becomes very heavy

•Speedometer dropped to zero while driving (\~30 mph)

•Engine stalled and would not restart once battery voltage dropped

What’s been done so far:

•Battery replaced (recent)

•RAC attended breakdown → confirmed no charging

•Original alternator replaced

•Second brand new alternator fitted (£380)

•Still no charging

•Fuses checked – all OK

•Alternator wiring/connection checked – OK

•Basic OBD scan shows no fault codes

Jump start allows the car to run, but voltage does not increase and the battery drains again.

Dash shows “Charging system malfunction – Engine could stop unexpectedly” (photo attached).

Engine bay photo attached as well.

Previous diagnostic showed "faulty alternator", but at this point, two alternators failing the same way doesn’t make sense.

Question:

On this generation Mazda 6 Skyactiv, could this be a DC-DC converter / charging control / i-ELOOP-related failure that is electronically disabling the alternator?

What specific tests should be done (voltage measurement points, battery current sensor, LIN communication, modules) before replacing any more parts?

Any Mazda tech or Skyactiv experience would be massively appreciated