There is a QSPI device on jetson NX and jetson Nano. This device includes some bootloader binaries.
When you replace the jetpack version on sdcard image, what you changed is only on sdcard.
The version on QSPI does not get upgrade/updated. For example, if you always use sdcard image but never try sdkmanager, then no matter what you’ve installed to your card, the bootloader on your NX QSPI is always that one flashed in factory. We don’t guarantee the version from the factory. Maybe it is from jetpack4.2.2, jetpack4.3 or 4.4.1.
Theoretically, even old bootloader shall work with new kernel from sdcard image. However, if the software on QSPI is corrupted, then replacing sdcard will not bring it back.
But just remember that this is just a try from software. I also asked to switch the board too because we cannot guarantee if this is a hardware defect.