... The latest firmware is supposed to be able to control the fans, did you check they were set correctly? Also see if you have set chip voltage and frequency settings in that particular miner and try if letting it auto adjust works better.
The issue was indeed broken fan. I can confirm, that temperatures in latest BOS are reported correctly and miners are restarting once temp2 hits 95C. Thank you for your help with downgrade command, maybe someone else will find it useful.