Canon 7D mark I just died...help

I used my camera yesterday, all was good, today I was planning to take photos and the camera would not come on. The battery is fully charged and I put a new lithium battery thinking that was the problem but nothing is working. Has this happened to anyone???

Check the battery door and battery door switch to make sure they are fully closed and working. Then check the CF door as well. These are the easy things to try first.

^What they said. I thought that my old 7DII died a while back, then I discovered that a tiny plastic tab on my battery grip that signals to the camera that the battery door is shut had broken off, so the camera wouldn't power on.

As above. My battery door on the 7D wasn’t closing properly. Canon fixed it for me w/o charge while I waited.

I checked all the doors and they seem fine, don't know what else it could be

Check the backup battery. The button cell battery is located inside the mainbattery compartment.
When I had my 7D I once had an empty mainbattery.
Overtime the backup battery became empty as wel.

I replaced it today: still not working

Use a non-bootable CF card without MagicLantern.

Canon Amateur wrote in post #18886342
Use a non-bootable CF card without MagicLantern.

I don't use magic lantern and don't know what a non-bootable cf card is.

anitaw2 wrote in post #18886583
I don't use magic lantern and don't know what a non-bootable cf card is.

It's pretty straight forward. A CF card that has software on it that Canon recognizes as bootable will try an load that software first before. A CF card with nothing on it, or images only is not bootable by the camera. In either case, that will not cause the camera to not power up but if you inadvertently put in a bootable CF card, the camera would try an boot from it but it would still power up. My guess stays, it's either the CF or battery door, the door switches, or something internal. One question, does the battery charger think that the batteries are fully charged? How old are the batteries?

gjl711 wrote in post #18886678
It's pretty straight forward. A CF card that has software on it that Canon recognizes as bootable will try an load that software first before. A CF card with nothing on it, or images only is not bootable by the camera. In either case, that will not cause the camera to not power up but if you inadvertently put in a bootable CF card, the camera would try an boot from it but it would still power up. My guess stays, it's either the CF or battery door, the door switches, or something internal. One question, does the battery charger think that the batteries are fully charged? How old are the batteries?

I have 3 fully charged batteries and a new lithium battery, nothing worked. It came on last night but when I turned it off and on again, it died again.

gjl711 wrote in post #18886678
It's pretty straight forward. A CF card that has software on it that Canon recognizes as bootable will try an load that software first before. A CF card with nothing on it, or images only is not bootable by the camera. In either case, that will not cause the camera to not power up but if you inadvertently put in a bootable CF card, the camera would try an boot from it but it would still power up. My guess stays, it's either the CF or battery door, the door switches, or something internal. One question, does the battery charger think that the batteries are fully charged? How old are the batteries?

I don't believe that to be the case. I am not sure we can say that Canon looks at the card first and boot from that source's firmware. When we first install Magic Lantern in fact, the install actually changes the camera to look to the card first, and after that initial install, the camera will then look to the card, but that isn't the factory default. At least that is what I remember from all the ML discussions and the boards over at ML. If it was the other way, ML users wouldn't even have to run any install, we would just put the firmware for ML on the card and the camera would run it.

At this point is it just the body or is a lens attached? I would detach the lens for testing so there are less variables.

Also, what firmware is it on?

anitaw2 wrote in post #18886706
I have 3 fully charged batteries and a new lithium battery, nothing worked. It came on last night but when I turned it off and on again, it died again.

I wonder if your on/off switch is cruddy or has something going on with it. If sometimes, it comes on and you can use it, but then you turn it off and try turning it back on again, and it doesn't respond at all, it feels like your on/off switch could be suspect? If you can get it to turn on, just leave it on. Many people never turn off the camera. Off isn't really off, it just means to turn off the displays and don't listen to button presses, but it is still on watching for things like battery door open/close, memory card open/close, new card put in, etc.

TeamSpeed wrote in post #18886736
I wonder if your on/off switch is cruddy or has something going on with it. If sometimes, it comes on and you can use it, but then you turn it off and try turning it back on again, and it doesn't respond at all, it feels like your on/off switch could be suspect? If you can get it to turn on, just leave it on. Many people never turn off the camera. Off isn't really off, it just means to turn off the displays and don't listen to button presses, but it is still on watching for things like battery door open/close, memory card open/close, new card put in, etc.

problem is when I turned it off, it didn't come back on.