Finding chip for inverter

Good day Everyone

I am a newbie in this DIY pursuit for power independence and joined this forum te reduce my school fees.

I bought a low frequency, 6kW, 48V Five Star inverter (FS181201) with a solar controller on Facebook Marketplace for an amount I couldn’t refuse, but when I connected it up at home, it didn’t work. When I opened it, I saw a few lightly burnt wires, but nothing serious.

The seller disappeared, but I thought I might get it fixed way below the cost of a new one.

The Five Star agent in the Good Hope China Mall in Johannesburg wasn’t interested and lack basic PR-skills. Apparently this model is too old to fix.

So I took it to an electronics technician and he found that we just need to change the microcontroller.

MUST in China, who have built this model back in the day, are still trying to find a chip for me, but they are busy for a while now.

I sent out a few more emails, and is still asking around, but no joy. Since this inverter was available in SA and (later models?) are still available in the market, (picture below), It must be possible to find a unused, secondhand, or damaged one with the chip intact.

Is there a person who can help me, or point me in the right direction please?

(sorry for the dark pictures taken during load shedding and the dirty display screen, I stuck tape on it to protect it)