ill try my best to help you on this,
if it says err-3 it wont allow you to enter the code.....your locked out at this point
you can try taking the battery cables off for about 5 minutes and then replacing them.... i believe this should allow you to get back to the main screen to enter the code.
i read somewhere online, that you could touch the positive and negative cables, with the ignition off and not hooked up to the battery and this would reset it, but id be iffy on that.
if you get it to the screen where you can enter it you should be all good.... if after 5 min it doesnt work, you may have to go to the dealership.