Adding OpenWrt support for Mikrotik hAP ac 3 [RBD53iG-5HacD2Hn]

Unfortunately "upgrading" the firmware to 6.46.6 isn't possible on my device :(. Any idea if routerboot is still broken with v7 or RCs?

Do you really want to upgrade firmware? [y/n] 
y
ERROR: can not change firmware to this version, please try newer one