I have a phoenix multiplus 1600VA which is only 2 months old and has just stopped working. I was charging the batteries from a generator and running a high AC load (washing machine), which was all working as it should. When I turned off the generator, it didn't switch back into inverting mode. All three LEDs (inverter, charger, and alarm) were flashing. I tried reinstalling the firmware but this didn't work. I turned the generator on, and it kept repeatedly cycling on/off.
It has now started working as a charger again. When you connect AC in, it goes into inverting mode briefly and then charging, but when you disconnect the AC in it just switches off. Could this be some problem with the internal relay or something? Is there a fuse somewhere that might need replacing?