Camera refuse to turn when CF Card is inserted

[DeRouge]

I have been using my 5D MK II for several years now without problems, and recently, more precisely this past week, I have started using ML to try to shoot RAW.
I used a Sandisk 16GB 1066x initially and it worked fine for the moment, but I realized that it shoots too little footage on that memory count, so I bought a Lexar 1066x 256GB online, I could not format it in camera and it remains unformatted.

However, the problem now is that the camera turns on fine without CF, but as soon as any CF is inserted, the camera appears powerless.

Could anyone help me? I am leaving in two days for a trip, and planned to shoot some videos and stills during it.

Thank you very much!!!

[Walter Schulz]

Check for bend pins in CF slot.