The only VMware supported way is making backups from within the NSX Manager. Image-based backups are not supported.
If the NSX manager appliance breaks, and VMware Support can't (or refuses to) fix it, you throw it away, deploy a new one, point it to the backup location and import the last good backup and reboot. All from inside the appliance GUI. That's the only correct way.
I've seen funky stuff happen where people did a complete VM restore (Veeam or other products, does not matter) and the NSX Manager started doing the funky chicken afterwards because it was never backed-up in a truly consistent manner. And VMware Support will hang up on you, because you used an unsupported method to make backups.
If a component other than the NSX Manager has a problem, you just re-deploy it. One does NOT back-up controller- or edge-appliances. Always re-deploy. That's what happens during most NSX upgrades too: the admin upgrades the NSX Manager and it upgrades all the other components by deleting them and deploying a newer version (rip-and-replace) and injecting the configuration again (which is stored in 1 location only: the manager).
I'm sorry to say this, but it's all very well documented in the NSX Documentation...
This is a general problem with virtual appliances using built-in databases etc. The various vendors devised methods to backup and restore them correctly. Just "Read The Friendly Manual".