if you are getting ceros, the most probably couse it's the library for the IR. Reinstall or updeate the library, sometimes you have to reinstall more than one time. That should work. About media keys, the keyboard library doesn't have media keys funccionallity, so you need to use another one. This one worked for me https://github.com/NicoHood/HID after you install this library you have to change your code. The code for pressing media keys is different, you have to use Consumer.write for example Consumer.write(MEDIA_VOLUME_UP) for vulme up. You cab find the name of every key here https://github.com/NicoHood/HID/wiki/Consumer-API
for normal keys just use Keyboard.write() if you want i can send you the code I made to do this.
I hope this was helpfull