X1 Electrical / Parasitic Drain issue - please help.

[motodreams]

2013 x1 xDrive35i. 185k kms.

Looking for any help I can get here. I've been though many of the 'normal suspects' as well as had car in import shop. No luck. Coles notes at top, more detail below.

-Car dies when left overnight. Systems are being woken up.
-trans light goes off (told indicator computer off), problem is intermittent, call it 50/50 it will be dead in am.
-neg battery cable replaced, battery near new, active handles disconnected on pass side as not working, driver's works and not warm.
-shop has gone through all systems, disconnecting and reconnecting as they go. Intermittence drove them to give up.
-FRM replaced by shop. No change.
-No issues while driving EXCEPT 2 'electrical system failure warnings' of 1 sec each over a 4 month period.

Car has always had a high battery discharge warning during winter since I got it 2 years ago. Its got worse going into this spring and culminated with the car dying almost constantly overnight. The negative battery cable has to be removed or the car will be dead in the am.

The car has been into an import specialist. The guy spent 8 hours of diagnostics and incorrectly diagnosed as the FRM. It was replaced (at my cost) which did absolutely nothing. They have had issues replicating the problem but when I took it home from the shop (a 5km drive) it was dead in the am. They've given up without any ideas.

I have replaced the battery and the neg battery cable.

No codes or other indications of problem. I have had a 2 1 sec 'electrical system failure' show up during which the speedo dropped then everything returned to normal. Both times at hwy speed, once cold, once when car was hot. These were about 3-4 months apart.

First time car was in shop for week. disconnected pass door, issue went away for a week. Drain came back the day after the first time I used the headlights.

SO intermittent issue, seems to return with driving. The system failures are v concerning but who knows.

I am sure its all related but don't really know where to go next. Any ideas on bits or pieces to replace?

Do I take the car to the dealer? Based on market value it hardly seems worth taking it in. I can only imagine what my bill will look like.

I can provide the diagnostics notes from the shop if that's of help. I am aware of the blower resistor being a potential issue but would have thought that would have come up during diagnostics if it was problem.