OOF. Try a different lens, but that doesn't look good. I find it curious that the edges of the distortion are soft, it doesn't go all the way across the frame, and how it's a little curved along one edge..
What's most interesting is the black shape in the first picture that occludes even part of the bright bar. Whatever that piece is, it doesn't belong there at that time. If I had to guess, I'd say that the shutter mechanism is in the process of disintegrating.
"100% sure a broken shutter."
Sorry but Peter is correct. It is toast. It is probably not fixable either as the cost if you can find a new shutter will be more than another used camera.
Look for a nice used 1Ds Mk II.
Why? Now that early members of the 1D series are finally falling apart, they've lost their principal advantage: their legendary durability. At this point, a used 5D Mk III (of which there should be a glut, in view of the enthusiastic response accorded the 5D Mk IV) figures to be a much better buy.
B from B,
Why? I'll tell you why. First off there is nothing like a 1 series. There is 1 series and then there is everything else. Another good reason a good used 1Ds Mk II can be had for $350. A very nice one for $500. Even though the Ds2 is a granddad by now it can still hold its own. Once you use a 1 series you ain't gonna go back to any lesser camera.
If the OP wants a 1 series FF a used Ds2 will be less than a new shutter for the Ds if he can even find one. Of course if he really wants to step up, there is the Ds3, But they are still pretty pricey. There is a huge difference between the Ds2 back and the Ds3 forward.
09/26/2023: New firmware updates are available.
08/18/2023: Canon EOS R5 C training series is released.
07/31/2023: New firmware updates are available.
05/31/2023: New firmware updates are available.
05/18/2023: New firmware updates are available.
03/30/2023: New firmware updates are available.