My 2007 Mercedes LSK 280's trunk will not open; warning light on dashboard indicates it is open; neither my key nor a second open it; interior latch on dashboard will not open it; batteries are wo

It sounds like the trunk release actuator is defectve or there is a wiring problem

Try opening the trunk using the same key used for the ignition.
The key hole is next to the passenger side taillight

Are you gettin a "trunk ajar" light and the trunk is closed? If so, probably the indicator switch is defective. It's on the inside driver's side of the trunk. (The remote will not work if the trunk is open or if the switch is defective & not contacting the stopper properly.)

WHAT YEAR IS IT, MAY BE YOU HAVE THE KEY SLOT TO LOCKED TRUNK, TRUCK SHOULD BE OPEN WHEN DOORS ARE OPEN, UNLESS YOU HAVE A VALET KEY AND NO PERMISSION FOR THE TRUNK TO OPEN, IT IS NOT THE REMOTE, ID THE KEY OR THE KEY POSSITION ON THE TRUNK.

Hi,
Google found THIS:
Turn key to position 2. press the button to show the service due light. release button. turn key off. press and hold the same button to view the service light, within 2 second turn key to position 2. wait up to 10 second and the light will reset to show new service. This may take a couple of trys (make sure the doors are shut).gL,
Td

check the wires near the hindge

Isn't there botton somewere on the door or left lower conner of dashboard to open trank remotely?

That light means that you are setting the tire pressure guage. there is nothing wrong with the van.

Service B means that there is a major service due. Brakes are not related. You will get a break warning light when they are due. The B service includes Oil and filter, Interior dust filter, Tire rotation, check of all the fluids, Lubricate all door and trunk hinges, and engine air filter. Also brake flush every 2 years.

I hope all you want is to reset the service indicator and this is how you do it.

Tum the key to position one, scroll using the arrows on your steering wheel until the service interval or indicator is shown,press the reset button for at least 2 seconds (the reset button is the one you use to reset the trip meter or increase and decrease light intensity of the dashboard). The display will ask you whether you want to reset service interval, press the reset button again and this will reset your service interval.