Well, I think after you update your firmware to other firmware it might be the reason of the temperature increased.
The only thing that I think it could help you to decrease the temp is to increase the fan speed,
I bookmarked a solution and I hope that you can try it first and increase the fan speed check this
https://bitcointalk.org/index.php?topic=2690140.0If this could not work you must try the other firmware I suggest that you download this Antminer-S9-all-201705031918-550M-user-Update2UBI-NF.tar.gz
It could reduce your frequency settings and reduce the miner temperature.