E550_ME

My 2011 E550 Started up with a slight delay but wasn't much.. Was a pretty hot morning and made my first stop. Got back in and car started fine and headed to my second stop. Car failed to start and noticed brake pedal was solid and unmovable. Took the keyles go button out and still wont start. Got it home (towed) and replaced the battery with a new glass mat battery with enough AMPS to start the car. Lights don't dim when I try cranking the engine so replaced the starter fuse and the starter relay. Still no joy.. Now was told if the brake isn't depressed the car won't engage the starter, but was also told that using the key I don't need to have the brake depressed. So which is it? Is it the power assist causing the issue where i can't engage the brake switch or is it my starter that's toast? Any ideas?

Mr. Toad

I thought all modern cars required the driver to depress the brake pedal before attempting to start.

E550_ME

That's what I thought that you had to depress the brake past a certain point for the car to be able to be started. However the expert service advisors (don't get me started on that) who I have talked to say different. Now my thought is if I can't depress the brake I can't engage the switch that tells the vehicle it's safe to start. So this seems to hint the brake booster system isn't holding a vacuum.