Xiaomi gateway 3 - Downgrade firmware

I need your help. I bought a xiaomi gateway 3 and wanted to add it to HA. I found this integration https://github.com/AlexxIT/XiaomiGateway3 and tried to install it. However it was not working and I noticed that I had already updated the Firmware.
I found here (https://github.com/AlexxIT/XiaomiGateway3/issues/87#issuecomment-719467858) how can I get back to the old firmware but I don’t understand anything they talk about.
I also don’t know how to weld, and I don’t have the equipment for that.
Someone can help me?
For now, I just wanted to integrate the hub so that I could turn off the light with an aqara zigbee interrupor. Do you know another solution?