Pardon the upcoming text wall... Just trying to get as much info out here so maybe someone can have the best chance to help me. I have a Samsung Galaxy S5 (DoCoMo branded SC-04F/SM-G900D). I was using a stock rooted ROM on Android 4.4.2 and felt the need to upgrade. Backed up EVERYTHING with TiBackup and Dropboxed it so that's not a concern.
Upgraded process went smoothly, but now my PAD opens to a black screen with a teal bar on top that says 'PAD'.

Troubleshooting done so far, but to no effect
* Cleared PAD cache and re-installed.
* Cleared Google Play Store cache, uninstalled updates
* Cleared Google Play Framework & Services cache (trying to reinstall G-services right now - slow mobile connection :-/ )
* Google Play app opens to a mostly gray screen with menu options. Cleared the cache on it as well.
* Tried hiding the su binary with 'Hide my Root'. SpaceX has the SuperSU apk by default. (I've read online that I should also rename the Superuser.apk, but I'm not quite sure how to do that).

If anyone has any tips or other things I can try, then I'd greatly appreciate it. Worse comes to worst, I guess I could always try upgrading my phone to the Stock Lollipop rom, root it and then manually remove all the DoCoMo bloatware (blah...). Many thanks in advance for any help!

EDIT:
More Details. I'm on the NA server. Google Play Services reinstall didn't help.