Tucson not recognizing key fob
 

Car in garage for two days. Went to start it and nothing. Test battery its good. Change battery in fob nothing. Car won't even come on to run OBD.. I'm not sure what's next. Any suggestions

The mechanics I use and trust has suggested it's the on board computer.
all suggested will be helpful.

It would help if we knew the year and also if it had push button start.

The Tucson is a 2017 and has pushbutton start.