Bitmain Warranty did not say what the problem was. The board they repaired is still running fine 3 months on.

I was a bit surprised as I thought they may just return me any old repaired board but it was actually the same board I sent out there. I recorded the board serial number before it went and the same board came back Smiley I did have to mail them quite a few times for status updates and the were a bit slow replying to mails.

It cost me £18 to ship to the US $175 for the repair, $25 for the postage US to UK and then, the real stinger, £46 import duty.