Where are you located? For US residents, you just need to open a repair ticket and send the defective unit to CA repair center under warranty. Bitmain shipped a new D3 from china within 2 days of delivery of my defective unit to CA repair center.
I recommend to send it to bitmain, only if you are in europe and want to fix it quickly I am willing to fix it, honestly this is not a business for me, have to drive 80kms to the guy with the tool, have to use one of my hb to extract the original file, so its a pain in he ass.