How to randomize filenames with BATCH file command?

I have a directory which contains *.mkv video files. The names of each files looks as following (1 of 2 ways):

...S01E01....mkv

...S01E02....mkv

...S01E03....mkv

or

...101....mkv

...102....mkv

...103....mkv

... (and so on...)

I need to automatic randomize file-names, but the names must contain the SXXEXX pattern.

As result, for example, Hello.World.S01E02.Example.mkv can be renamed to S01E02_AsdfCg4Gjy531G32dH5A.mkv, and Hello.World.804.Bla.Bla.mkv can be renamed to 804_ds3DFghF3xcvT5433H1s.mkv

How it could be done with simple batch file and windows command prompt?

Thanks.