New Inverter CB tripping

Woonz

Beginner
In December, my neighborhood endured a week of electrical repair and maintenance work. After resuming the electric supply, there were enormous voltage swings which eventually wrecked my Microtek inverter.
Upon inspection, I was informed that it had something to do with the IC and that the only remedy was to purchase a new one or spend 5k on the existing one. (I didn't bother to get a second opinion).
Anyway, I opted to get a new Microtek inverter.

Now, anytime I try to use my geyser, the CB trips and shuts down the electricity of every appliance connected to the emergency backup. I then need to manually reset my inverter.
My geyser is not an appliance connected to the emergency backup, thus I'm curious why it causes the incident. No other appliance, whether in emergency mode or not, trips the inverter.
I had the geyser switch fixed a few months ago when I was on the old inverter, but I did not have this problem.
The electrician blames the inverter technician, and vice versa. The remedy is to not use your geyser.

Can someone help me identify the genesis of this problem? Does it have to do with faulty inverter connection setup or something else?

I can provide additional/ relevant information in required.