I have 1DX serial number 073012000688.
Recently updated firmware to 1.2.4.
On Saturday 15 June 2013 at 12:49:42 I was using camera 073012000688 with a 180mm Canon Macro Lens and a 32 GB Lexar 1000X card to take photos that are required for evidence in a financial dispute. The Canon 1DX went dead on me and has been dead ever since. I was forced to fall back on my Samsung cell phone, not the same resolution, or image quality, but at least it works when required to do so.
There is absolutely no response from the body, no indicator lights, black screen dead as a door nail.
Removed battery, swapped batteries, left powered down for several hours, nothing, nada, zilch!
Camera has 15k exposures since new, December 2012.
Possibly linked to firmware upgrade?