Sorry, you can’t reprogram the button’s function, but you can replace the top cover assembly replacing the failed buttons.
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Sorry, you can’t reprogram the button’s function, but you can replace the top cover assembly replacing the failed buttons. Here’s the guide to do it [https://www.ifixit.com/Guide/Canon+EOS+5D+Mark+II+Top+Panel+Replacement/33383] it’s a bit of work and tricky! You might want to find a good camera repair person to do it.