Hi
from the boot log, i noticed you're JUNOS 15.1R5. Could possibily hit this PR:
https://prsearch.juniper.net/InfoCenter/index?page=prcontent&id=PR1265386
On EX2200/EX3200/EX3300/EX4200/EX4500 and EX4550 platform, type "boot -s" from loader prompt can start up the system in single-user mode. The user can setup the password recovery in that mode. If "boot -s" is typed under loader in 15.1R1 ~ 15.1R6, the system does not go into the single-user mode but reboot from the alternate slice.
As a workaround, remove "boot_unattended" environment variable from NVRAM. The removal is temporary. The change does not persist after the password recovery.
Please follow the following steps:
1. Get into u-boot prompt (=>) by pressing [Ctrl + C] key combination at the beginning of the system boot process.
U-Boot 1.1.6 (Feb 6 2008 - 11:27:42)
Board: EX4200-24F 2.20
EPLD: Version 6.1 (0x85)
DRAM: Initializing (1024 MB)
FLASH: 8 MB
USB: scanning bus for devices... 2 USB Device(s) found <<<<< Type Ctrl + C here
scanning bus for storage devices... 1 Storage Device(s) found
=>
2. remove 'boot_unattended' environment variable
=> printenv
bootdelay=1
baudrate=9600
.
.
boot_unattended=0
.
=> setenv boot_unattended
=> printenv
.
<<<<< /* boot_unattended is not listed anymore */
3. Then issue "boot" command, get into "loader>", boot -s will work
=> boot
Consoles: U-Boot console
Found compatible API, ver. 7
FreeBSD/PowerPC U-Boot bootstrap loader, Revision 2.1
Hit [Enter] to boot immediately, or space bar for command prompt. <<<<< press "Space" here
Type '?' for a list of commands, 'help' for more detailed help.
loader> boot -s <<<<<
..
System watchdog timer disabled
Enter full pathname of shell or 'recovery' for root password recovery or RETURN for /bin/sh: recovery <<<<< enter "recovery" here
warning: Please logout and log into the VC-M to use CLI.
{linecard:0}
root>
{linecard:0}
root> configure
Entering configuration mode
{linecard:0}[edit]
root# set system root-authentication plain-text-password
New password:
Retype new password:
{linecard:0}[edit]
root# commit
2010-01-01 00:31:54 UTC: Running FIPS Self-tests
veriexec: no signatures for device. file='/sbin/kats/cannot-exec' fsid=75 fileid=51404 gen=1 uid=0 pid=304
2010-01-01 00:31:57 UTC: FIPS Self-tests Passed
commit complete