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TCK is not toggling
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TCK net is showing 2 Ohms to GND
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Can be regarded as synonymous, I think. There's nothing to measure except locating the short. You should be able to detect by voltage drop method, if it's near the FPGA or the JTAG connector. Unfortunately, it's difficult to clearly distinguish FPGA internal from external PCB short near the FPGA without desoldering the device or using x-ray. Possibly, an FPGA internal short reveals by a voltage drop at FPGA supply pins when soucing a current to TCK.