Repair cost is different on each case due to what is broken. If you busted the ASIC it will not be cheap. Most are in the range of $25-$250 range depend on what is broken and how many items are broken. some are getting free repair if those unfortunate ones that experienced manufactures defect be repaired with just the return shipping, however, those are very rare as most damaged hash PCB are user caused or environment related damages.
Also, if unit was aquired from bitmainwarranty.com warranty work is all performed locally in USA, Russia, Ukraine and Venezuela and some are cross shipped based on the nature of the damages. (user caused damages vs defect)
"user caused or environment related damages" are not covered under warranty, so why won't Bitmain Warranty specify to the paying customer what damages they are paying to fix? If I take my car in for repair, the repair shop tells me what the specific problem is that I am paying for. If I have a hash board that is inop and I pay you to fix it, you should be able to tell me what you fixed on it.
I also think the explanation of "user caused or environment related damages" is bullshit and Bitmain is refusing to own up to faulty equipment so that they will not be on the hook financially.