Rough idle and blank Display
 

Have F15 X5 3 L N55 yesterday, it stumbled on start, restarted it, drove a little and parked at a store, came back after 15 minutes, had very rough idle on start, and all kinds of warnings came on. Shut it down and restarted started and ran OK, but the display screen was blank. This morning it started right up and the display screen was back on, no codes or check engine light. Scratching my head as to what could be wrong, apprecitae the help

I would begin by checking battery voltage and doing a load test. My experience with the E53 was that you only get 3-4 starts on the engine once the battery reaches failure point. There's very little "cushion" time before a replacement is necessary once the battery starts to go.