Studio Display firmware glitch: no more brightness adjustment, camera and sound

About 4 days ago display started to behave weird: speakers, camera and mic are no more recognized, and brightness is stuck at mid level and cannot be adjusted (only reduced with software apps like Lunar or Brightness Slider).

There is NO firmware version in Graphics info.

I restarted the display by unplugging for 5 minutes-1 hr already like 30 times - and there is nothing else I can do!

Apple Configurator does not recognize it.

There is no Apple Store or official support in my country as well! Company who sold it says we will send it far away for looong time so it's not an option.

It started when i used Sonoma, now updated to Sequia - didn't help.

What are my options? It worked perfectly for first 2 months, and ofc I use original thunderbolt cable from correct socket with no other USB-C devices and m3 macbook air.

Already did Safe boot several times and NVRAM reset. Tried with friend's mac - same issue, it is display's firmware that got corrupted.

Any ideas how to install original firmware?