Check the connections. You said the lights went off when you were driving...and since your alt is putting out 14V, I don't think it's the battery.
I think maybe just your cable connections might be loose...cable, or ground...and I wish I could see a connection besides that with them doing the FP...but I'm not seeing it. Pull up on the cable connections to the battery to make sure they're tight. Simplest explanation is that they disconnected the battery when doing FP and didn't tighten it back on.
As desperate as this sounds, in comedy, 'likes' and 'views,' 'friends,' and 'retweets' really help. If I've ever helped you, please help me by friending, liking, viewing, and retweeting. It makes others think I have a following...it'll take you a minute or less. If you could, I'd really appreciate it!
A recent set--NSFW audio: https://youtu.be/_dcxcZfD6dg
Mangofy your E46!