(Although the files are small, they are rare. It's very effective. At first, I was unsuccessful in filling os. It turned out to be a problem with the loader boot program. After the upgrade, junos can be installed. If you don't believe me, try it too. At first, I poured it, and it always goes directly into the loader mode. Have you tried it? Otherwise try it.
uboot.txt
Including multiple files, please download and test by yourself!)