Building for a custom board (Based on existing) - No boot.

I am coming from a yocto build for a dev board. I had to make u-boot patches, kernel config changes, and custom DTS tree.

I'm trying to adapt this to Armbian, one step at a time. I started with building am image for sk-am62b.conf.   I did not expect u-boot to boot from correctly.
I was glad to see console messages, but expectedly, u-boot didn't continue.

I made a new board config for this, duplicating sk-am62b.conf, but changing a critical line I made to get this to work previously.
 

TIBOOT3_FILE="tiboot3-am62x-gp-evm.bin"

Now, the boot process gets through u-boot and loads the Linux kernel.
However, the kernel halts because it cannot find the root file system.

Waiting for root device PARTUUID=26aa2b10-02...

I confirmed the device in u-boot, and it seems to agree.

Environment size: 5112/126972 bytes
=> echo load mmc ${bootpart} ${fdtaddr} ${bootdir}/dtb/${fdtfile}
load mmc 1:2 0x88000000 /boot/dtb/ti/k3-am625-sk.dtb
=> run finduuid
=> echo part uuid ${boot} ${bootpart} uuid
part uuid mmc 1:2 uuid
=> part uuid mmc 1:2
26aa2b10-02

I then modified my board config:
 

BOOT_FDT_FILE="myir-6254-am62x/myir-6254-am62x.dts"

But after booting, u-boot didn't acknowledge this:
(From the u-boot environment)
 

fdtfile=ti/k3-am625-sk.dtb

So, I finished applying my u-boot patches that I made under the Yocto build.
Some of these changes may be redundant:

edited: am62x_evm_a53_defconfig
+

CONFIG_DEFAULT_FDT_FILE="myir-6254-am62x.dts"
+CONFIG_TI_FDT_FOLDER_PATH="myir-6254-am62x"

After booting into u-boot, now I see the change made:
 

fdtfile=myir-6254-am62x.dts

Then I see this:
 

Running uenvcmd ...
14857759 bytes read in 983 ms (14.4 MiB/s)
36805120 bytes read in 1549 ms (22.7 MiB/s)
Failed to load '/dtb/myir-6254-am62x.dts'
libfdt fdt_check_header(): FDT_ERR_BADMAGIC
No FDT memory address configured. Please configure
the FDT address via "fdt addr <address>" command.
Aborting!
ERROR: Did not find a cmdline Flattened Device Tree
Could not find a valid device tree
Scanning for bootflows in all bootdevs

This is not unexpected either - since the files are not the image yet. When u-boot can't find the device tree, it loads a grub interface.
And when I 'e'dit that I see the line

linux /Image root=PARTUUID=076c4a2a-02 rootwait rootfstype=ext4

and change it to:
 

linux /Image root=/dev/mmcblk1p2 rootwait rootfstype=ext4

The kernel sees the rootfs, and proceeds to boot.

If I change it to using the PARTUUID, as above, it also boots.

If I manually place the DTB file where u-boot reported it is is looking (copied from my running yocto system) (in /dtb/)
The kernel boots, without the grub interface.
However,  the same situation occurs, where it is waiting for the root device.

Waiting for root device PARTUUID=26aa2b10-02...

I have a few things going on here.

I think in order to boot to an OS I need:
1) Solve why the kernel does not see the root partition when booting from u-boot (but does when I can get into the grub interface)
2) How to properly implement a custom device tree structure.   I know there are overlays, but I'd prefer to just drop in my whole custom tree.

Once I get there, I can proceed to implement some of the kernel modification I did within the yocto build environment, but this first.

Thanks for the assistance.