This KB documents the issue when a QFX10002 model device gets rebooted on its own and then stuck in Boot loop with "MGD not responding" log messages

Device will reboot on its own and will then stay in Boot loop with below logs seen during boot :-

could not open user interface connection: management daemon not responding
Retry connection attempts ? [yes,no] (yes) yes
could not open user interface connection: management daemon not responding
Retry connection attempts ? [yes,no] (yes)

This issue can be seen on both QFX10002-72Q and QFX10002-36Q device. In scenario when device gets rebooted on its own then there is a possibility that Boot process might not complete correctly thereby causing daemon like MGD to not work correctly during the boot process and thus bringing device in a Boot loop.
 
MGD daemon is responsible for parsing the configuration and then Validating and then committing it.
In a scenario if MGD is unable to respond then boot does not completes and device keeps on in a boot loop.
 
The best solution is to format install the device which can be done using below KB :-
 
https://supportportal.juniper.net/s/article/EX-QFX-Recovery-installation-for-QFX10K-and-EX4300-MP
 
 
If format install does not helps to recover the device then most likely device needs to be replaced.
 
Please contact JTAC in such scenario for further investigation.