Mass / batch – update / edit cells with in a grid

I am looking for some ideas on the UX of allowing a user to edit multiple cells in a grid at one time. These users may have thousands of records and they need to provide data on each record, this data may be duplicated across multiple records so I am trying to figure out a clean way to allow them to apply a value to multiple cells easily.

Hoping to not implement excel in my application.

Any help would be appreciated :)