Which I did, and looked as if it succeeded. However, on reboot and attempting to follow the same process:

U-Boot SPL 2024.01 (Nov 13 2025 - 19:31:27 +0000)
DRAM: 128 MiB
Trying to boot from MMC1


U-Boot 2024.01 (Nov 13 2025 - 19:31:27 +0000) Turing Machines, Inc.

CPU:   Allwinner R528 (SUN8I)
Model: Turing Pi 2 (v2.5)
DRAM:  128 MiB
Core:  73 devices, 25 uclasses, devicetree: fit
WDT:   Not starting watchdog@20500a0
MMC:   mmc@4020000: 0
Loading Environment from FAT... Unable to use mmc 0:1...
In:    serial@2500c00
Out:   serial@2500c00
Err:   serial@2500c00
Net:   eth0: ethernet@4500000using musb-hdrc, OUT ep1out IN ep1in STATUS ep2in
MAC de:ad:be:ef:00:01
HOST MAC de:ad:be:ef:00:00
RNDIS ready
, eth1: usb_ether
Setting bus to 0
Button key1 state: off
Hit any key to stop autoboot:  0
=> env set boot_unlocked 0
=> devnum=0
=> devpart=ubi
=> ubi part spi-nand0
mtd: partition "ubi" extends beyond the end of device "spi-nand0" -- size truncated to 0x7f00000
=> run distro_bootcmd
Boot device: mmc
Boot mode: normalboot
Saving Environment to FAT... Unable to use mmc 0:1...
Failed (1)
This is the first boot
Scanning mmc 0:1...
Running U-Boot script: /boot/boot.scr.uimg
919 bytes read in 5 ms (178.7 KiB/s)
## Executing script at 41900000
5561028 bytes read in 922 ms (5.8 MiB/s)
disabling write protection..
## Loading kernel from FIT Image at 42000000 ...
Could not find configuration node
ERROR: can't get kernel image!
SCRIPT FAILED: Continuing
UMS: LUN 0, dev mmc 0, hwpart 0, sector 0x0, count 0x1dd3800
couldn't find an available UDC
g_dnl_register: failed!, error: -19
g_dnl_register failed
BOOTP broadcast 1
DHCP client bound to address 10.1.136.11 (2 ms)
*** ERROR: `serverip' not set
Cannot autoload with TFTPGET

(N.B. This was setting

boot_unlocked

to take a look at the EEPROM state)