Did you checkt he obvious?
how about the switch?
Did you change the fuses anyway? Sometimes that can get hairline cracks undetectable tot he naked eye.
I recently just replaced all of my fuses for brand new ones..
'92 300CE - Sold
2004 C240 - C7 Wheels
2015 ML350 - P1, Pano, Ash poplar wood, Sport Dinamica interior, Running Boards Keyless go.