9.4v is too much, if you have to go over 9v, its better to reduce speed in my opinion.
And yes, assume that board is failing, don't expect it to work at spec speed anymore, if it works fine at 500mhz, so be it.
When you install BrainsOS, go and lower those voltages. Yes it loves 9.4v, but don't. I know someone that starts at 8.7v always. Hundreds and hundreds of S9s...
If you went back to factory firmware, it probably changed its ip, you'll have to find it again. Depending on how you made your bOS image, there is a small chance you cloned up the mac address. Plug the miner controller directly to a computer and scan its ip, log in and inspect the hw mac address and compare it with the second one, just in case.
There is nothing factory software can do that you can't replicate manually with bOS. If anything, the factory firmware is going to limit you more. Also bOS is over protective by default, since it reboots if over 95°C while factory might leave it running until 115°C or such. bOS is giving you a second chance to fix your overheating, while factory will happily burn it. More sales right?
Also as told elsewhere, the sensors tend to fail. That's when you appreciate bOS the more, with factory you would think the hash board is useless, but still works using bOS...