Turn off the switch.
Connect to the switch via a console cable:https://useopensource.blogspot.hr/2007/01/using-cisco-console-in-linux.html
Turn on the switch
During boot if some automated wizard starts to ask you for something, say no.
Once it seems to have finished booting press enter, and then you should see a 'switch>' prompt.
At that point it should work and you can disconnect the console cable.(Unless you wnat to configure the switch)
If it still won't work... Go back to the switch console(reconnect the console cable).
Switch# sh run
Switch# sh start
And shouw us the output of both the sh run and sh start commands here in this thread.
Let's go full CCNA mode!
Also, is it a second hand router? Did the previous owner wipe his old configurations?