Looking at the log file in comment 20, it does seem like the very first read from the Tegra USB device timed out. The most likely cause is that something had previously communicated with Tegra between when it first entered recovery mode and when tegrarcm_v2 was run. Please try resetting or power cycling Tegra and re-entering recovery mode, then see if tegrarcm_v2 works as expected or not. If resetting Tegra and re-entering recovery mode doesn’t help, then something else is going on which I don’t understand.