If this element is not available, the page uses the default wrapper configured for the site in the Admin interface. The steps above do not validate its authenticity, but it is downloading the file from Lenovo, so. I'm not sure why, but in my case the regular method failed on the step that validated the fimrware files authenticity.
Step 7 return to Web GUI Software Updates page and click Apply
Step 6 openssl enc -d -aes-128-cbc -in /mnt/system/upgrade/staging/firmware/upgrade.bin -k EMCNTGSOHO | tar -xzmf - upgrade.xml Step 4 cd /mnt/system/upgrade/staging/firmware Step 3 mkdir /mnt/system/upgrade/staging/firmware
(the password is the admin password prefixed by "soho") Step 1 enable "Allow remote access for support (SSH and SFTP)" from the page. Don't blame me if it doesn't work for you.
This made it so the update.html page said there was an upgrade available, but that's about all. I tried a bunch of things leading up to the final success, including sftp of the upgrade.xml from the decrypted tarball to /mnt/system/upgrade/auto/upgrade.xml.
I then applied the update by clicking "Apply" on the page.
I used the commands in the script, not the script itself, to download the firmware update, and get it ready to apply.