[j-nsp] Bricking EX4500 with 11.4R3 to R4 upgrade

[Tarko Tikan]

hey,

I just want to get this information out there for others. We've received 
a batch of new EX4500-40F (manufactured in march) with 11.4R1. They were 
upgraded to R3 without any problems. When upgraded from R3 to R4, they 
will boot once (during the upgrade process) but every subsequent reboot 
will hang before loader prompt leaving you with a bricked device.

Last thing you will see is "Consoles: U-Boot console". Investigation 
with JTAC is ongoing but it doesn't seem to be hardware issue as we have 
already bricked 3 devices (2 accidently, one while trying to downgrade 
to R3.

-- 
tarko