Building the "Desktop" image, I got:
HELLO! BOOT0 is starting!
boot0 version : 3.0.0
reg_addr 0x01f00100 =0x00007347
reg_addr 0x01f00104 =0x0000703b
reg_addr 0x01f00108 =0x5aa5a55a
reg_addr 0x01f0010c =0x000000ff
reg_addr 0x01f00110 =0x000000ff
reg_addr 0x01f00114 =0x000000ff
eraly jump fel
U-Boot SPL 2017.03-armbian (Apr 25 2017 - 15:56:39)
DRAM: 1024 MiB
Trying to boot from MMC1
U-Boot 2017.03-armbian (Apr 25 2017 - 15:56:39 -0300) Allwinner Technology
CPU: Allwinner A31? (SUN6I, id: 7)
Model: Merrii A31 Hummingbird
DRAM: 1 GiB
MMC: SUNXI SD/MMC: 0
*** Warning - bad CRC, using default environment
Setting up a 1024x768 vga console (overscan 0x0)
Error: no valid bmp image at 66000000
In: serial
Out: vga
Err: vga
Net: eth0: ethernet@01c30000
Hit any key to stop autoboot: 0
38518 bytes read in 147 ms (255.9 KiB/s)
switch to partitions #0, OK
mmc0 is current device
Scanning mmc 0:1...
Found U-Boot script /boot/boot.scr
3550 bytes read in 204 ms (16.6 KiB/s)
## Executing script at 43100000
U-boot loaded from SD
Boot script loaded from mmc
128 bytes read in 175 ms (0 Bytes/s)
4256917 bytes read in 484 ms (8.4 MiB/s)
6189880 bytes read in 593 ms (10 MiB/s)
Found mainline kernel configuration
40041 bytes read in 580 ms (67.4 KiB/s)
** File not found /boot/dtb/overlay/-fixup.scr **
## Loading init Ramdisk from Legacy Image at 43300000 ...
Image Name: uInitrd
Image Type: ARM Linux RAMDisk Image (gzip compressed)
Data Size: 4256853 Bytes = 4.1 MiB
Load Address: 00000000
Entry Point: 00000000
Verifying Checksum ... OK
## Flattened Device Tree blob at 43000000
Booting using the fdt blob at 0x43000000
Loading Ramdisk to 49bf0000, end 49fff455 ... OK
reserving fdt memory region: addr=43000000 size=a000
Loading Device Tree to 49be3000, end 49beffff ... OK
Starting kernel ...
Uncompressing Linux... done, booting the kernel.
And it Stucks at that point.