Unable to restore iPad Pro error occurred (-1).06A6.FFFF

My ipad pro 12.9 got stuck on restore screen. Tried everything. Reset, dfu mode. Different cables, different computers. Took it to apple genius today but they told me this is a new issue and only thing they can offer me is through warranty buy same model for $799……..but my customer rep told me i can try to downgrade the itune version to fix problem, which they are not able to due to apple policy. But if i am stuck on restore screen how do I downgrade. Please help

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