I recovered control board with sd file. I got it from Bitmain's customer service.
Now the whole miner isn't working. So frustrating.
Before it showed that invalid volt etc. but worked with two hashboards. After driving sd file none of hashboards arent working. Kernel log says something about temp sensor's type.
I think this is a crucial moment when I will send this to warranty repair.
2021-02-22 10:59:34 power_api.c:274:set_working_voltage_raw: working_voltage_raw = 1850
2021-02-22 10:59:35 temperature.c:297:calibrate_temp_sensor_one_chain: chain 0 temp sensor NCT218
2021-02-22 11:00:30 temperature.c:219:is_temp_sensor_type_correct: Wrong temp sensor type, chain = 1, sensor = 107, type = 0x0, retry.
2021-02-22 11:00:30 driver-btm-api.c:186:set_miner_status: ERROR_TEMP_LOST
2021-02-22 11:00:30 driver-btm-api.c:127:stop_mining: stop mining: Can't get temperature sensor type!
2021-02-22 11:00:30 thread.c:750:cancel_read_nonce_reg_thread: cancel thread
2021-02-22 11:00:30 driver-btm-api.c:112:killall_hashboard: ****power off hashboard****
EDIT: I upgraded firmware and now it is working again with two same hashboards as before. So sending to China for warranty repair is not compulsory right now. I will do it later. My warranty expires end of this year. Miners bought from antminerdistribution gets warranty of two years. So I have time left.