One.To avoid the distribute of virus in the firmware, which can trigger damage to the ANTMINER S19 series, the setting functionality of “Safe Boot” continues to be switched on and also the “Root Authority” function has been disabled. In case you haven't gained your refund however, be sure to Verify https://bitmainantminers21hyd90602.aboutyoublog.com/38714921/new-step-by-step-map-for-antminer-bitmain-t21