Anyone know why my 5D has frozen?

read the instruction manual it is probably not in proper mode .

Remove the lense, or the film if you're willing to waste it, and check to be sure the shutter blades aren't damaged. It'll be fairly evident if they are. If they are, the camera is pretty much now a paperweight. I hate to tell you that - but shutter replacements are VERY expensive and parts for most of these models no longer available from Nikon.

If that is not the issue, set the mode dial to M and try to take a shot. If that also doesn't work, either the batteries are exhausted or there is an internal issue in the camera. At this point, try new batteries. If that also gets you nowhere, you'll need to seek a reputable service tech, either through Nikon directly, locally if you can find one, or online/mail-order. If you have to go mail-order/online I'd recommend KEH Camera out of Atlanta, GA. They are very reasonable, have decent turn around, and do good work - but expect at least 1 month without your camera.

In M(anual) mode, be sure the lense is also set to M, via the switch on the front of the camera near the lense mount. You're not worrying about the quality of the image, only if the camera will take one. In manual mode, the light meter and other functions will have NO bearing on anything the camera does or doesn't do. At this point the meter reads out only for your information for you to set the settings yourself. The batteries do everything else - firing the shutter, driving the motor, etc.

First try pressing the DISP or DISPLAY button on the back of your camera. If that doesn't help, astuck shutter is another common failure mode for digital cameras. The symptoms of a stuck or "sticky" shutter are very similar to CCD image sensor failure. The camera may take black pictures (for shutter stuck closed), or the pictures may be very bright and overexposed, sometimes with lines, especially when taken outdoors (for shutter stuck open). To confirm a stuck shutter, put the camera in any mode other than "Auto", and turn the flash OFF (you don't want to blind yourself for the next step). Next look down the lens and take a picture. You should see a tiny flicker in the center of the lens as the shutter opens and closes. If no movement is seen, then you likely have a stuck shutter. If so, please see this link for further info and a simple fix that may help.

For this kind of pictures, Don't try to focus on a lightning, it is to quick and mabe the overall brightness is not enough for your camera to focus.
So you can try to focus on something at infinity, if you manage then, put your focus on manual before re focusing, this way you will be able to take as many pictures as you want.

You can also try to focus manually directly.

And for you information the best way to take a lightning picture is to put your camera in bulb mode, use a remote control, open the shutter and close it as soon as you'v seen a lightning.

Hope this helps.
and good shooting !

A few suggestions: The mirror lock up function has been activated. The sensor cleaning mode has been activated, doing this the camera as soon as you trip the shutter the mirror will come up and all other functions of the camera are inoperable. the mirror will stay in that position until it runs out of battery or you turn it off. The part you said about having to removing the battery doesn't make scents for this function though. Sensor cleaning is in the Custom Functions.
I know you said regardless of lenses and batteries how long do you wait before shutting the camera off and removing the battery? I know that's a question and we aren't suppose to answer a question with a question but the reason I'm asking is that the Canon 40D has a long 30 second shutter speed and a "bulb" setting. It is possible that the camera has been set to "AV" and the shutter is timing out, OR it's been turned to BULB and that mirror will stay there until the camera battery is dead before it drops. Couple things to check out before the next thing I'd think about is the amount of shutter actuation. The Canon 40D has a shutter good for 100,000 clicks/actuation. Sounds like a lot but if you are doing time laps or extended video it's very possible to blow the shutter out of these.

The reason for these lines is your shutter sticking or not firing at all.
The video function should be unaffected due to it not using the shutter and is the easiest way the determine the fault.
What causes it is moisture residue building up on the shutter leafs.
On this model if camera it is quite difficult to rectify because the shutter mechanism in side the lens is a sealed unit. It can be done however but takes longer than other models of fuji camera because of this sealed unit.
Cheapest option would be to find a second camera for donor parts. Even if it is damaged you can still remove the shutter mechanism and swap it over.

You mention everything except the shutter speed. When the aperture shows "Lo" it's saying that there isn't enough light at your selected shutters peed to produce a good exposure. That's why you have dark photos. You may need to bump the ISO up higher, or use exposure compensation to make it work well. For a football game, 1/750 is nice, but you can usually make 1/500 work.

Normally there are two reasons for the given problem.

1). Bad or defective CCD. and/or

2). shutter not working.

in the first case the only solution is the replacement of the CCD. and in the later case sticking of shutter blade, non functioning of shutter blade will cause the problem. This can be rectified by sending it to some repairer.

is it on manual status? maybe it's not in focus.
what other stuff do work?

Most likely, you have changed the AF point, which only takes effect in the creative modes (Manual, Av, Tv, P, etc)

There should be a button on your camera that has a grid like pattern above it, like
-
- - - - -
-

or so. press that, look through the viewfinder, and move the shutter or rear wheel, you should see the different AF points like up in red, and as you turn different ones will light up, and eventually all of them. also, you can look on the screen on top (or back, if its a rebel) and it will show you which ones are selected while in that mode, instead of looking through the viewfinder.