We see a lot of posters that have parasitic drains that mechanics cannot find. Some are simple; Cheap aftermarket radios, car alarms or remote starters. Some are much harder to find.
I found this YouTube channel a while back and I like this guy’s approach to diagnosis of the causes of problems. I watched him use an orderly, step-by-step, sequence to find the most unlikely cause for a huge parasitic drain in a Hyundai Genesis. Skip to the end if you want the cause but it is entertaining to watch him find it.
Post below your thoughts as to how it happened and why the “cause” even exists!