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.
If you look real close to you see any new chips? Board modifications? I'm doing S9 board repair and the problems that cannot be seen cosmetically are always the most difficult. I'm always gathering information on past repairs (there's no sense in reinventing the wheel).