Bentley Battery Junction fuse box
 

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I have a 2006 Bentley Continental flying spur with 32,000 miles. I believe 3rd owner. Started geeting white Battery low at start up. Car running rough and Trunk wasn't shutting right (would cycle up and push rear right up when appeared shut). There was NO dash lights on, first battery red light showed up today. I took down to shop and they said zero cold cranking main (Bosch non AGM battery H8).. So I decided to replace battery main to see if this was issue. When taking off the Fuse junction box the bottom of one of the bolts seemed melted. This is the 904 on attached diagram. What is this for? I replaced battery and everything running no lights or issues. Im just concerned about the melting. One last thing I hear the clicking after a few seconds like battery switched over which is weird. Key is started on right side turn