I really appreciate the input. I hate electrical problems so I start out irritated. I have done the disassembly 4 times as I thought I found the problem each time. I have reached the limit of my patience.

I don't have any of the usual ignition switch symptoms. When I have a no start condition there are no dash lights at all, nothing works, it is as if the battery is removed. However, there is 12+ volts at the battery but 0 voltage at the terminals under the hood.
To the best of my knowledge the cables from the battery to the terminals under the hood have no breaks, one solid wire and go directly to the under hood terminals. Can a bad ignition switch also cause my problem?

If I am not off base, I can think of only two possibilities. The cutoff switch in the back is sometimes breaking the circuit even though it is in the correct position or the backside of the positive terminal under the hood is doing the same thing.

This has happened several times with no common circumstances. The last time I was at the wheel alignment shop. It started normally and drove normally going there. When tech unlocked it to take it in I saw angel eyes come on as I have them wired and were normal brightness. When tech tried to start it. there was nothing. No power to anything and multimeter at underhood terminals was 0. No angel eyes, nothing. I called AAA and it was going to be 1.5 hours. I waited a half hour and decided to jump it. It started and after letting the engine run for a few minutes I decided to see if I could make it home. Got home, shut if off and it started normally. I won't have to have my hair cut for a very long time.

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X5 4.6 2002 Black Sap, Black interior. 2013 X5M Melbourne Red, Bamboo interior
Dallas