It is possible to open database after incomplete recovery even when files are inconsistent. Use the instructions in one of these posts:

[Recovering an Oracle Database with Missing Redo](https://www.pythian.com/blog/recovering-an-oracle-database-with-missing-redo) by Simon Pane

> recovering without consistency is not supported and should only be attempted as a last resort. Opening the database with the data in an inconsistent state is actually pretty simple. We simply need to set the "_allow_resetlogs_corruption" hidden initialization parameter and set the undo management to "manual" temporarily

> Now, will the database open? The answer is still: "probably not"

> To put it simply this ORA-00600 error means that a datafile has a recorded SCN that's ahead of the database SCN

> The solution to this problem is quite simple: roll forward the current SCN until it exceeds the datafile SCN. The database automatically generates a number of internal transactions on each startup hence the way to roll forward the database SCN is to simply perform repeated shutdowns and startups.

> switch back to automatic undo management using a new undo tablespace

> Finally the database is opened (although the data is inconsistent) and the "old" data can be queried

https://www.parnassusdata.com/en/node/1135