2009 E350 Key does not work
 

I am having trouble with my remote. It does not lock/unlock the car or turn in ignition. I don't have keyless start so the car is dead now.

I think the same thing happened twice in the past. Once a few weeks ago, I drove my friend to shopping, I remember I could not use the remote to lock the car. When I manually locked the car, it unlock itself after I closed the door. So I had to leave the car unlocked. But it was fine after we got out. It happened again this week and was fine after a few hours. Now it is dead.

I changed the remote battery and checked the fuse. I followed instructions online to inspect the remote. I can see the red light flashing but no IR is visible with my phone camera. If it is a remote issue, would that prevent me from turning the key to start the car also? The remote itself is $350 so I don't want to order one without knowing for sure that is the problem.

Many thanks for your help,

Jane