Repairing a Apex plus 2000VA inverter

[Lowku]

Hi guys

I have this inverter that i am trying to rapair. Its a APEX PLUS from TESCOM 2000VA 24V to 230V DC to AC power inverter (see photos). The mains of were connected to the output of the inverter (wrong side). Initially i opened it up and all the mosfets on the (input) BATTERY side were shot, so i replaced them all. I checked all the fuses and but nothing else looked bad. When i plugged it in, it gives a continues beep and red light (meaning fault). when i plug in the AC side the inverter works as it should, but when the AC is removed there is no power anymore.

If anyone can help me on figuring out if their might be a protection circuit of some kind that might have blown after the MOSFETS blew or some circuit diagrams that would be very useful.

Thanks in advance

[station240]

There is a connection to the battery supply to get an initial start voltage, most likely a simple resistor. Start by tracing what components besides the mosfet are fed off the battery. Should be easy enough to follow the PCB traces.