Steps to recover from a Loader prompt ( Loader> )
There may be situations if a unit has failed to load the kernel during boot process and displays the below message:
can't load '/kernel' can't load '/kernel.old'
Press any key or space bar to enter into the loader prompt. < After pressing space bar or any key you would be directed to the below prompt >
To recover from this situation, below procedure can be used.
12. If the unit has the updated/desired verison then skip the step number 13.
13. Run command # run request system reboot slice alternate to get the new version of Junos stored in alternate partition, in case required.
14. Now the new unit is ready to join the VC or master.
15. Make the connections and check the status of new unit . After this, the unit would get the configuration from master once joined in VC.
step 13 is not correct !!!! Take care you are requesting a reboot and start from the alternate partition !!!
CORRECT is # run request system snapshot slice alternate
This index kb explains all the various prompts that an EX switch might end up at when it fails to load Junos and provides links on how to correct that situation.
Can't get to the Loader Prompt (loader>) Loader Prompt ( loader >)Debug Prompt (db>)UBoot Prompt (=>)Can't load kernel error'Loading Junos' reported on LCD panel
EX switch – Troubleshoot upgrade failure/crash – System stuck on Boot-up
I had the same problem but my EX2300-C was not in a boot loop, not able to even get to the loader, what I end up doing was opening the unit, there is a mini usb port inside that connected directly to the internal memory, since those partitions are freeBSD, i was able to mount those with a virtual machine, and edit the files on both partitions.
Even thought that was the way i solved this, i think it could be a good idea to default a switch and create a iso or img image of the internal memory using the DD command over Linux so if it happens again, you just need to connect over usb and reflash the internal one.
Other tip, is to backup the envs from the U-boot environment. I have mine, but for each device its totally different. I have rescue couple of SRX and now one EX by troubleshooting directly from uboot.
If you have any questions, or if you need help, ping me directly firstname.lastname@example.org