If you want, upload a close-up photo of the T580 board’s test-point area and I’ll mark the exact pads for ISP.
Signal cross-talk or voltage mismatch. The ISP cables are too long. Solution: Shorten cables to under 15cm. Add a 100-ohm resistor in series with the CLK line to dampen reflections. t580 isp pinout
Lenovo thoughtfully (or frustratingly) includes an unpopulated header footprint labeled . This is your goldmine. It is located near the edge of the board close to the docking connector. If you want, upload a close-up photo of