Finding one blown fuse is luck. Finding the same fuse blown twice is a diagnostic clue.
Located on the right side of the luggage compartment behind a removable cover. This box ( F4 ) handles rear electronics, including the trailer hitch and rear climate control. Common Fuse Assignments
Look for a small red plastic fuse puller clipped inside the cover. You will also find large relay blocks here for the starter and fuel pump.
Your fuse box also contains relays (black or blue cubes). A bad relay can mimic a blown fuse. Common relays in the 2007 GL450: