uboot start fail after download and flash my own uboot

[sunzhijin]

i have a board with iMX8 QXP,the board ddr4(3GB) and emmc(32GB) is the same as iMX8QXP_MEK develop kit.

i download uboot(rel_imx_4.14.98_2.3.3_patch) source code and compile it ok,then i use mkimage_imx8 to make my own flash.bin（contains bl31.bin/scfw_tcm.bin...）

then i use uuu to download and flash uboot to emmc,and i can download and flash it ok,and from the imx8 serial log i can find uboot download ok and flash to emmc ok,serial log is :

U-Boot 2018.03-00013-g0d6d880779-dirty (Sep 06 2022 - 20:33:18 -0700)

CPU: Freescale i.MX8QXP rev? A35 at 1200 MHz at 46C
Model: Freescale i.MX8QXP MEK
Board: iMX8QXP_ZHITO_MEK
Boot: USB
DRAM: 3 GiB
MMC: FSL_SDHC: 0, FSL_SDHC: 1
Loading Environment from MMC... MMC: no card present
*** Warning - No block device, using default environment

Failed (-5)
TX PLL is not locked.
In: serial
Out: serial
Err: serial

BuildInfo:
- SCFW c2c1675e, SECO-FW f449a0d2, IMX-MKIMAGE 25560004, ATF bb209a0
- U-Boot 2018.03-00013-g0d6d880779-dirty

MMC: no card present
Detect USB boot. Will enter fastboot mode!
Net: No ethernet found.
Fastboot: Normal
Boot from USB for mfgtools
Use default environment for mfgtools
Run bootcmd_mfg: run mfgtool_args;if iminfo ${initrd_addr}; then if test ${tee} = yes; then bootm ${tee_addr} ${initrd_addr} ${fdt_addr}; else booti ${loadaddr} ${initrd_addr} ${fdt_addr}; fi; else echo "Run fastboot ..."; fastboot 0; fi;
Hit any key to stop autoboot: 0

## Checking Image at 83100000 ...
Unknown image format!
Run fastboot ...
Detect USB boot. Will enter fastboot mode!
flash target is MMC:1
MMC: no card present
MMC card init failed!
MMC: no card present
** Block device MMC 1 not supported
Detect USB boot. Will enter fastboot mode!
flash target is MMC:0
Starting download of 973824 bytes
.......
downloading of 973824 bytes finished
writing to partition 'bootloader'
support sparse flash partition for bootloader
Initializing 'bootloader'
switch to partitions #1, OK
mmc0(part 1) is current device
Writing 'bootloader'

MMC write: dev # 0, block # 64, count 1902 ... 1902 blocks written: OK
Writing 'bootloader' DONE!
Detect USB boot. Will enter fastboot mode!
Detect USB boot. Will enter fastboot mode!
Detect USB boot. Will enter fastboot mode!
Detect USB boot. Will enter fastboot mode!
Detect USB boot. Will enter fastboot mode!
Detect USB boot. Will enter fastboot mode!
Starting download of 21836288 bytes
..........................................................................
..........................................................................
..................
downloading of 21836288 bytes finished
Detect USB boot. Will enter fastboot mode!
Starting download of 89787 bytes

downloading of 89787 bytes finished
Detect USB boot. Will enter fastboot mode!
Starting download of 10826441 bytes
..........................................................................
........
downloading of 10826441 bytes finished
## Loading init Ramdisk from Legacy Image at 83100000 ...
Image Name: fsl-image-mfgtool-initramfs-imx8
Image Type: AArch64 Linux RAMDisk Image (uncompressed)
Data Size: 10826377 Bytes = 10.3 MiB
Load Address: 00000000
Entry Point: 00000000
Verifying Checksum ... OK
## Flattened Device Tree blob at 83000000
Booting using the fdt blob at 0x83000000
Using Device Tree in place at 0000000083000000, end 0000000083018eba
Disable gpt0@5d140000, resource id 207 not owned
/dma-controller@591F0000, 62536
/dma-controller@599F0000, 63500
/dma-controller@5a1f0000, 61584
/dma-controller@5a1f0000, 61584

Starting kernel ...

but when i power off and power on board again ,i can see nothing from serial log,even no log is ouput in uboot period,so i do not now what happened,i do not know whether uboot is boot ok or not

and i do not know how to analyse this problem.