Driver's door intermittent power supply problem

[tony2506]

Mégane 3 1.6 DCI 2012 GT line Stopstart. Hello, problem started a few months back when driver's door window opened in short bursts instead of fully auto. Then I noticed the door was not locking. Now, all electrical power is lost. The door open sensor is working ok. I have changed the switch module with no difference. Here's a strange thing, power restores itself intermittently, but only when engine running. If I open the door, leave it open and start the engine, 10 seconds later the power to the door is restored, door interior light comes on, window switches working. All other door locks and windows working from each door switch. As soon as engine off, power is killed, interior light dead when all others on. Door will not lock. This is a wierd head scratching problem. Could it be a dodgy solenoid perhaps?