Impossible to say, I have no knowledge of the Renault Master.
I base my diagnosis of a faulty starter motor on generic knowledge of motor vehicles.
The last time I did this was on my late lamented Suzuki Vitara (magic little vehicle for what it was).
Often, electrical items which are un necessary for the engine starting process are turned off to minimise electrical load, so leaving the battery to give all its enerigies to the starter motor.
From time to time I have seen people with no technical knowledge, turn on the lights (including headlights) before starting a car in the depths of winter, and wondering why it does not start!
JimB