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Check the IO board for a burnt chip. If the chip has a spot like the picture below you need to replace the logic box.
If the logic will not boot and there is no spot in this IO board, reseat the board and try again.
disconnect all wires from the back-plane (seen below) except the DC12 which powers the logic. If it boots up at that point you have a short somewhere in the cabinet.
Re-seat the Bios chips. This step may be necessary as we swap the bios chips when replacing the logic. The bios chips are needed to for the logic to boot.
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