OP I'm glad you still have the patience to work with things like this and figure out what's going on. 30 years ago maybe I could have but with age and chronic back pain I've found I hardly even have the patience and nerves to do an oil change any more. I still do lots of my own work but with my pain/anxiety I often find myself wishing I'd have paid someone to do the work. Really gets to me when it's something I know should have taken 1-2 hours and I spend all day on it.
I don't know about MB but I've been told that flooded/rebuilt title should decrease the value by 20-40% on most cars. I bought my '16 Nissan Versa with a rebuilt title and 10K miles in Feb. 2019. As I recall the clean title book price on it was something like $9800 when I bought it. I bought it for $5300 which was about 46% below clean title book price. It now has 31,xxx miles and has been absolutely trouble free. When I bought it at that price I figured if I could get it to around 100K miles with no major problems I'd be money ahead.