Check the aux battery, First time it will check the aux battery's status, it not allow to start if it's too weak, but will ignore it and direct start from main battery @ second try.
I plan to try 2 things if happen again after dealer’s work, jump start to N1 & main negative to identify aux battery failure; try to start on 4L to identify “clutch position sensor” issue. Wish me lucky!
As my understand, fused jumper is to pretect overflow current to damage Aux battery connected equipment. In this case, jump start cable direct to N1 w/o this jumper should be safe, but using battery pack which generates big current in short time might need the fused jumper to protect those low...
Does jump cabel work for you? My less one year new JLUR could start 3 times under -15c, It shows 11.9v to 12.1v on dash but no attemp to crank, all dashboard, lights are working, cabel jump over 5 mins not working, roadside service use 2 huge jamp packs not working, but it will start at next...