Which exactly DUT board is in question?
Is POR behaviour of the reset signals on the DUT board similar to shown in the "Figure 6. Power-On Reset Sequence" in the QorIQ LS1028A Reference Manual?
Is the DUT board capable to boot?
Please confirm that JTAG interface is implemented as described in the AN12028 - QorIQ LS1028A Design Checklist, 5.20 JTAG pin termination recommendations.
Is TRST_B asserted during power-on reset flow?