Coachman Caravan strange electrical issue

I have very recently purchased a 2020 Coachman 545 VIP. The first weekend away we had a strange electrical issue. Firstly the TV, microwave, and fridge were having power outages. Then the Aldi heating control would flash on and off rapidly, and the lounge and bedroom spotlights flashing and remaining on even if they were turned off beforehand. On the main control there is a message 'Engine running' & 'some appliances maybe disabled'. Has anyone else experienced similar problems. We are very new to caravaning, and the dealer is struggling to replicate the problem.