Innosilicon simply remove these miner from farming and shipped to us.
So they lied by saying it is refurbished machine. They didn't event took time to check it. Will never buy from Innosilicon again.

Anyway, to fix the problem, you need to make a firmware update but the firmware is specific to the machine which means you will have to send an email to Innosilicon support with :
 - your order ID
 - Serial number
 - MAC address
 - DNA of the machine.
To find the DNA, they ask me to download Security Tool software (they gave me this link : https://drive.google.com/u/0/uc?id=18p3lwB9UrBDgTJjI3CCfWJVM-ggRxstu&export=download maybe you can find the software on their website)

After sending all these, I received the firmware update, upload it and I was able to change the Pool settings ! HOURA !

Hello,

I had the same problem.
Ordered 2 miners, one has the fixed pool setting, can't change it.
Can you please share the firmware ?