I'm a little confused by your wording.
Did you try each board one at a time to determine which one is not working?
Did you try each data port with that board to determine it is the board and not the port it is plugged into?
Did you try using a different cable to determine if it is the cable?
If you have determined that after the above it is the board and you are still under warranty then you should be able to get it repaired. You could also possibly get it repaired if not under warranty, but it will cost you.
yea I have tried all of these things and determined which board it doesn't work .... and i'm still under warranty until now
Since you have been following the advice from Bitmain Warranty for the testing, the only thing affecting warranty status is the 90-day time limit.
I had a b11 board go out -- still technically under the 90-days -- but sent it to BitmainWarranty anyway for them to do the repair/exchange.
Got it back 1week later, cost was $145 inc the return shipping. Yes was a little higher than sending to China for (possibly/probably 'free') repair but:
1. I was able to ship the board to BitmainWarranty using USPS insured for full value. I declared $400. Sending to China you have to declare value under $40 or face Customs scrutiny and the associated extra cost/time it takes, so if it gets lost or damaged in-transit you are screwed. USPS fully insured w/tracking was $21.
2. No issues with who-did-what, what on it died and is it covered by warranty, etc.