of the corresponding database please? Maybe it was set in crs to only start in mount state.
If that is so, you may change that with srvctl modify database.
BTW: It would help to post some more information. E.g. Version used, etc.
However it could also be that the database goes only into mount mode, because there is an error opening it from clusterware side. Had an issue where the DB was using a wallet stored in ACFS, and could not automatically start, because ACFS was not mounted.
Have you checked the alert.log of the database for errors?