Beware of the current LEDE snapshot, it bricked my NBG6616. It's now in a boot loop and it doesn't even get far enough for reflashing via TFTP. I don't have a TTL to USB module (yet) so can't really diagnose this further or try and fix it via console...
I have used lots of LEDE snapshot builds on my NBG6616 in the past with no issues whatsoever. I updated via LuCI and checked the sha256sum like I always do, so it seems like there's something wrong with the firmware itself.
Here's the build which bricked my router: Sun Mar 18 06:29:09 2018, sha256sum becb106db9b14390585901cc5ac084a36f5b9a5cc5d9abc9701b489e497f9854
EDIT: Nevermind, I did manage to reflash it via TFTP. I just didn't realize at first that I had to push the WPS-button for quite a long time during boot...
(Last edited by jackster_ on 18 Mar 2018, 15:14)