Seems pretty simple to me, you ordered a ready to run tank, it arrived broken, you send it back. End of story. Contact the vendor and ask for a call tag (shipping voucher?) to send it back and return it for a refund or a new tank. How did you pay? Paypal? Credit card? Either of those can be contacted to file a claim if necessary and once that happens most vendors will just give up and send a call tag and then a new unit. I wouldn't even think about repairing it. An item that expensive should be in good working order when you take delivery, and besides, who knows what else may have been damaged and just won't show up until you run it for a few hours. Some part that should last the life of the tank may have taken a hit and will now fail in a couple of months.
Again, stop even thinking about it and focus on getting it returned for replacement or refund.