I called UPS and also double checked my invoice for my import code.
UPS is useless. They say that it's the government that assessed it, so I need to talk to customs in order to challenge the assessment. They have no information other than that the government assessed the fee, and they (UPS) need to collect said fee before delivery.
Checking my invoice from Bitmain, the specified HS/HTS code is 8471.50.0150. I can't find this code in the two links you provided (@efudd). So I'm not sure how my item is assessed such high duties.