I would try doing a couple soft resets (Hold power and home button), and if that doesn't work, try putting the original battery back into the phone and then soft resetting. It could just be a bad new battery, but worst case it could be the tristar chip on the logic board.
From what I am reading, the iMacs use odd socket sizes (FCLGA 1156) and that through some experimentation, one user tried upgrading his i7 to a better one of the same socket size, but it would not boot. I don't believe Apple has any firmware restrictions that would prevent you from upgrading, but I think the issue came down to it not providing enough wattage to the new CPU. Here's an fairly detailed article on the CPU's of your particular line of iMac. http://www.everymac.com/systems/apple/im...-aluminum-faq/imac-intel-aluminum-processor-upgrade-instructions.html
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