I backed up my router configuration using the "backup" button in WebFig 'Files' menu and when I try to restore from this file (same router) using the "restore" button, the router seems to be a brick, not responding to the configured ip and not appearing to wifi networks. What did I do wrong???

I also tried to connect to it using its default factory settings, no luck.
I also tried to reset it and then restore again, same result, goes to a brick after restore attempt.

RouterOS version is 6.44.1

Reinstall RouterOS using Netinstall and then restore configuration.

Don't forget backup on your computer your backup file.

Regards.

Maybe this help, it's my more deep way of NetInstall, please read.
HowTo NetInstall