I have a Antminer S7 Batch 8 with a problem access the root,
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- 4th. I decide to update the firmware
- 5th. I reboot the system, but this time doesn´t sound as usual when the miner is conecting (fan coolers do not change speed from minimum)
You might go into more details on this part. A bad flash can mean issues such as not mining or being able to access miner. I believe on firmware update they reboot on their own. Did you let it update and reboot on it's own? You mention you rebooted it I'm hoping you did not try this or other thing's during firmware update.
A good rule on firmware for most part if it's working leave it alone. Did you ever have miner working? If so what was last change before it quit?