It is rare for a flash to brick any Jetson…mostly there are issues with an attempt to use a VM, or else a problem in download or preparation of operations. An example would be that you’re probably using over 20GB of host disk while flashing a TX1 and the host might not tell you that you’ve just run out of space.
I usually recommend installing via command line instead of through JetPack if there are issues. This is the smallest possible set of operations one can use to flash. Here is an older URL on command line flash, but you’d want to use the R28.2.1 driver package and sample rootfs:
You’d also want to use the original micro-B USB cable which comes with the Jetson since some of the other cables on the market are really just charger cables and their data abilities are questionable.