I have about ten Jetson Nano cards. Some of these cards are turned on by connecting the power supply, monitor and SD card. But some of them do not turn on with the same power supply and monitor and SD card.
I did the following test. I replaced the main board of the healthy card with the board carrying the defective card. The nano card was turn on.
But the opposite of this test, i.e. replacing the main board of the defective card with the board carrying the healthy card, resulted in the card not turning on.
Are these dev kits (SD card models whereby the SD card slot is on the module itself, and not on the carrier board)? If so, consider that dev kits have QSPI memory which contains boot content. If the boot content is not compatible with the release used to create the SD card, then it won’t boot correctly. In cases where the Nano cannot boot on any of the SD cards, I suggest flashing again (use an Ubuntu 18.04 host PC). Pick the same release as that from the SD card (for release see “head -n 1 /etc/nv_tegra_release”, which is the L4T release). L4T releases are listed here (and particular JetPack releases are tied to particular L4T releases): https://developer.nvidia.com/linux-tegra