In rare cases, FPC might go down on a QFX5200 device which will bring down all interfaces as well. This KB explains this issue and possible ways to troubleshoot the same.

All interfaces went down on the device. FPC went down:-

lab@qfx> show chassis hardware detail no-forwarding

Hardware inventory:

Item       Version Part number Serial number   Description

Chassis                WXXXXXXXXXXX

Pseudo CB 0

 ada0  9316 MB QEMU         QM00001      Virtio Block Disk

 ada1  4096 MB QEMU         QM00002      Virtio Block Disk

 ada2  512 MB QEMU         QM00003      Virtio Block Disk

 ada3  1024 MB QEMU         QM00004      Virtio Block Disk

 usb0 (addr 0.1) EHCI root HUB 0   Intel       uhub0

 usb1 (addr 0.2) product 0x0020 32  vendor 0x8087   uhub1

This issue can be both hardware and software-related.
Below are some steps which can help to fix this issue.
 
 

1. Power drain the device as the issue might have been caused by  incorrect boot and may get resolved after power draining the device

2. If the power drain does not help attempt format-install on the device using the below KB:-

 
https://supportportal.juniper.net/s/article/EX-QFX-Procedure-to-format-install-QFX5K-device-using-a-USB
 
 

1. If none of the above helps then the issue is most likely a hardware failure. Please open case with JTAC to validate and create an RMA.