Error while HL7800 Firware Upgrade

I’ve got this error while I trying to do update FW on a HL7800EV version1.2.1

F:\Downloads>sft.exe -p COM8 -b 115200 -j -s AppFW_flash.bin sysHeader_backup.bin.alt1250 sysHeader.bin.alt1250 sysHeader_modem.bin.alt1250 u-boot.bin ue_lte.fw partmap.bin ue_lte.fw2
SFT v2.10.2101.0 Jan 29 2021 10:37:07
File to download: sysHeader_backup.bin.alt1250
File to download: u-boot.bin
File to download: sysHeader.bin.alt1250
File to download: partmap.bin
File to download: AppFW_flash.bin
File to download: ue_lte.fw
File to download: ue_lte.fw2
File to download: sysHeader_modem.bin.alt1250

Using port COM8 at 115200 bps

Attempting communication at 115200 baud… success
Synchronizing with module…
AT port detected. Trying to synchronize with bootloader…
Synchronization success.
Flexible partition map detected
Flash mapping retrieved.
Using new flexible mapping.
Turbo mode not available.
Downloading sysHeader_backup.bin.alt1250 segment 1
Starting download of 0x410 bytes
[==================================================] 100 % (4.55 KB/s)
Waiting for download end
Erasing flash…
Error while downloading sysHeader_backup.bin.alt1250 - aborting download
Failed to unprotect flash

How can I resolve this.

what is the setting of AT+KSIMSEL?
Is it OK to upgrade FW by AVMS?

KSIMSEL response is

and I don’t know what is the meaning of ‘AVMS’

Thanks jyijyi.

you can see here: