This problem doesn't sound related to the IBS.
However the IBS is a plastic box maybe the size of a pack of cigarettes and is in-line on one of the battery cables maybe 6 inches or so from the battery post connection.
The purpose of registering it with the system is so that the car knows it is a new battery and it doesn't need to be charged as aggressively as an old battery.
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Also Mini can act funny when a battery is going bad. Have a load test done on the battery. Also check all your connections and grounds and make sure clean and tight.
How old is the battery?