I don’t know what you means by “carrier board is not populated”. The carrier board is responsible for supplying power to the module and for some of the power sequencing. The module PMIC drives RESET_IN low as part of the power sequence, so it would make sense that it would be low if the sequence didn’t complete properly. RESET_OUT is driven low when RESET_IN is low, but after the system boots, it can be driven low to reset just Tegra & the eMMC. On our carrier board we connect it to the powergood output of the 1.8V supply on the carrier board, so it would be held low until that supply is high to keep Tegra from booting too early. I would expect it to be low whenever RESET_IN is low.
Please refer to OEM DG pin descriptions for RESET_IN# and RESET_OUT#, check the basic connections in the power block diagram in the power section.
Besides, why you just have the “power_btn pulled up”? For how to configure TX2 for Auto-Power-On, please also check the OEM DG.