Yes I did but their response as in the past is very slow and with minimal words! You have to chat 3-4 times by mail that will take an average a week to get the problem solved. Very poor technical support.
Also the firmware is not available to public.
There's no public firmware for nano 3 they keep it private you can't just download it without an account from them.
How can you say it's bricked? How about the built-in screen is it turned off?
Can you able to access the unit through their app?
Since you said you already did the factory reset it means that you can still able to access the unit but it's not hashing. Would you mind to check if there's a API logs on the unit you can maybe find the reasons why it's not hashing from the logs.
I don't know the version that you use to upgrade this unit but you can try to flash the unit with the firmware available from this link below it might be the older version.
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https://bitcointalk.org/index.php?topic=5480799.msg64138633#msg64138633But downgrading is risky it might brick the unit and end up with no power.
Since there's not so much information, guide, and solution that we can see publicly the best option for now is to contact support or try to send it back to them for repair.
You said they are slow try other support emails they can maybe respond faster here are two contact emails that I know
avalonsupport@canaan.io and
customerservice@canaan.io