Sounds like a known issue. Download the following version of firmware, interrupt the boot process, load the image via TFTP, let it boot, then upgrade to 6.3r23.
https://download.juniper.net/software/firewall/ssg5ssg20.6.2.0r4-ef2.0
Sounds like a known issue. Download the following version of firmware, interrupt the boot process, load the image via TFTP, let it boot, then upgrade to 6.3r23.
https://download.juniper.net/software/firewall/ssg5ssg20.6.2.0r4-ef2.0