UEFI bios update stuck after debian based update to 5.1.2 from 5.1.1

Could you try to put a SD card in slot but still use SDKM to flash into your NVMe?

After you run this command ,there should be many logs showed on your serial console to indicate it’s doing upgrade. Please share these logs for further check.

Actually, you could also enlarge the size of NVMe SSD after boot up into the system.
Or refer to the following workaround.
JetPack 5.1.2/L4T 35.4.1 is now live - #9 by kayccc