So I followed the "more help" link at the bottom, and it said:
Failed to download a required update. Please check your internet connection and try again.
Errors: BLZBNTBTS00000046, BLZBNTBTS00000048, BLZBNTBTS0000004A, BLZBNTBTS0000004F, BLZBNTBTS00006, BLZBNTBTS00000052
My Internet connection is, of course, fine. I'm not sure what else to do at this point. I tried uninstalling and reinstalling my battle.net client with no luck. When I am able to launch my battle.net client itself, which is rare, it asks me to reinstall both Hearthstone and D3, both of which I have installed already, and it won't let me go online on battle.net. I've gone over the other potential fixes, including disabling my security programs, running a virus scan, and closing background applications, and none of these things resolved my issue. Not sure what else to do anymore.
Thanks in advance for any help.