1.To prevent the spread of virus inside the firmware, which might result in damage to the ANTMINER S19 sequence, the setting function of “Protected Boot” has been switched on along with the “Root Authority” function continues to be disabled. If approved, your refund will be processed inside of 7 days. https://finnaaxfs.topbloghub.com/40942322/antminer-bitmain-t21-an-overview