EOS 40d flash problems

[hegelegatt]

Hi! I am having problems with the flash on my EOS 40d. I get a message saying a incomp. flash or flash's power is turned off. I think this started after another photographer attached his external flash to my camera (no idea what flash he used). What can I do to fix this so I can get my internal flash to start working again?

Thanks!

[jfo]

This advice might apply:

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@bud411 wrote:
Had that happen to my T1i, turned out the micro switch in the rails on the hot shoe was stuck. After removing the metal plate & freeing it up with a small screwdriver, it's never done it again...

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[hegelegatt]

How exactly do I go about doing this? Thank you so much!