HELP what have I done to my phone?

[fotyc]

I was attempting to make a phone call on my S4 - it kept saying 'dialing...' and not going through. I was attempting to hit end-call or back or something else to get out of this call, and I saw a message that said something like "MMDI code running" - it wasn't exactly that but something like that - then I got back to my main screen but had no network connectivity. I restarted the phone, and instead of the little cosmic Samsung swirly thing on the black background that you get during startup, it was a black screen that said "SAMSUNG Custom" and an unlock icon, which I then touched to get to the unlock screen. I have no idea what I did, I have been running stock Android on this phone since the beginning. I don't want custom anything. What did I do? Can I undo it?

ETA I shut down again so I could go into recovery mode and wipe the cache - I can't get into recovery mode anymore but it did finally boot with the ordinary visuals. Are there some settings I should look at, to see if I've done something to the phone? I don't know why I can't get into recovery mode now.

 

[VidJunky]

Unless someone responds that has experienced this I would say this is a good question for XDA Developers.

 

[fotyc]

I'm not registered over there - and I looked up the subject and everyone over there who came forward with a solution presented one that only worked for people who were rooted, even though half the people with the problem were not rooted.

 

[Shane Calm]

Then ROOT the thing!! Xda is not known for bs answers i assure you! If you cant root it I can help ya.