Canon EOS 400D will not power up replaced both batteries still no go although when a new main battery is inserted and the camera is turned on the green indicator lights and will not turn off until the battery is removed.

Hi,

please make sure that canon isn't blocking certain batteries from being used. You can also check that the batteries work by placing them into other devices and testing them. If you have an adapter please use that to attempt to power the camera.

Thank you.

Have you tested the batteries and also is the back up battery charged?
Is the CF card inserted correctly if so then time to visit your local photo shop!

There is a small backup battery in the main battery compartment. I believe the XTi uses a CR2016 battery. It provides backup power to maintain the camera's settings when the main battery is removed.
Bob Kilbourn www.camerarepairs.com

1.Remove the battery, lens and CF card. Allow the camera to sit without power for 20 minutes and then reinsert a fully charged battery.
2.Turn the camera on and push the shutter button as if you were taking a picture.
3. If you don't get the error message reattach the lens and insert the CF card.
4. Check the below canon eos 400d service manual link:
http://goo.gl/LHYVAy

it will help you to save a lot of money
Hope it helps, Thanks

Did you overtighten the tripod screw?

Please see this page, on Safari Books Online - an excerpt from Canon® EOS Digital Rebel XTi/400D Guide to Digital SLR Photography which describes the steps in detail.

Here is a link which may help you.
http://forums.dpreview.com/forums/read.asp?forum=1031&message=9598105

It may be that the contacts on the lens is dirty, follow the directions, by using a clean pencil eraser (I would also suggest to use alcohol and clean the contacts after using the eraser). Also to remove the date button battery and the other batteries, then turn on the camera (with all batteries removed).
Then put the batteries back in.

The camera is working again. I took out the battery, with the the on/off switch, off. I then swtiched the On/Off switch On. I then put the battery in ,and the camera turned on.It then gave me an ERROR 99. I then switch it off and on again, and it is still working.

Try replacing the date/time battery located in the main battery compartment. Also, simultaneously remove the lens. This will be like a master reboot for the camera. Replace the date/time coin battery, the main battery (freshly charged) and lastly the lens.

If this doesn't work, send it in for service. If you are just slightly beyond your one year warranty, Canon may allow a grace period especially if you can provide a receipt. If you can't find a receipt, give them the approximate date of purchase when you send in the camera. You will need to call them or set up service online.

Hope this helps!

Try resetting to factory settings - here's how

• Firstly press the 'menu' button, then the up button above the 'OK' as many times as needed, until you see the top folders are highlighted.
  
  
• Press the right button near the 'OK' until you see the last folder highlighted. You will know this is highlighted when you see the first menu option that says 'Language'. The 3rd one down from that says 'Clear Settings'.
  
  
• Press the down button under the 'OK' until 'Clear Settings' is highlighted, then press the 'OK' button.
  
  
• Scroll up to your choice and press 'OK' to reset your Canon 400D back to default factory settings.

Now try - it could have fixed it. If not, keep turning the dial back and forth, and see if it jogs the camera's operating system. Try switching on and off. You should know, by the way, that the on/off switch doesn't really switch the power off - it tells the internal computer chips that you want the camera to switch off, and then the program closes it down enough to not respond until you either switch it on again, or take the battery out and re-insert it, when it will indicate a red light on the back of the camera to show the battery has made connection, then you switch on again; good luck - if not, phone Canon in your area