@gtj
did you have to add shortcut/ diode at j46?
we got controversial results because of the latter.
RTC setup wih cell coin in Jetson Nano Developer Kit 945-13450-0000-100 - #21 by Trumany
I believe for me it worked at once after the cell got installed but the other dev seems got stuck because of absense of the J46 diode
Jetson Nano Development board and RTC - #7 by rkasirajan
probably it is due to the differntce in the models of the boards used