Multiplus 1200 smoke after install

Hi, I have recently installed a Victron MultiPlus 12/1200/50-16 230V and upon testing the unit it began to hum loudly after several minutes. Then smoke started emerging from the bottom vent (the unit is mounted horizontally). I shut off the unit using the breaker switch. It was originally hooked up to a RCD which in turn distributed to two sockets. There were no devices connected to the sockets. I unplugged the AC IN and AC OUT and tried to start the device again. The same noise, shortly followed by more smoke.

I’m guessing it’s a faulty device? Does anyone have any idea what could be causing it? The unit is toast I’m sure. I will be applying to Victron for support and a warranty.

Just to note, the Multiplus unit is replacing a Phoenix inverter, with the same setup, just increased wiring gauge for the increased unit capacity, and the 230v hook up AC IN.

Did you have 12v connected ?

Yes, the 12v positive and negative were connected. The issue was also occurring when I unplugged the AC IN and AC OUT plugs, so it’s almost certainly an inverting issue.