Remove and reapply server input power， then everything is ok， Thanks very much.   
R630  with IDRAC  2.30.30.30, bios 2.0.1, upgrade firmware to 2.60.60.60,  then reboot hangup when "Loading BIOS Drivers...", and try many times with the same error.  downgrade IDRAC to 2.30.30.30, still hangup. try to reset idrac , still the same. [IMAGE]hangup    
dell r630 upgrade idrac cause boot hangup