Galaxy s4 4.4, no signal, return to 4.3 or 4.2

[steve song]

Hey guys, im new here and sorry if it is a repost but i didnt find any posts that solved my question...
So, i have a galaxy s4 i9505 and just updated to 4.4 kitkat google edition. My phone qas rooted. I successfuly updated, but there was a problem. NO SIGNAL. Maybe because i am from Brazil..
Do you guys know if it is a fixable issue?
If NOT, then, do you know how to downgrade my software to 4.3 or 4.2?? Just to warn, I lost my root access in the process, so it is possible to reroot even in the 4.4 kitkat? Because i know it will require root access to downgrade to another adroid version.

Thanks!

 

[JoeMcJoe]

Wrong section, this section for the GPe actual phone.

 

[srkmagnus]

OP, you might also still be rooted but are missing the SU (SuperUser) app, which you can download and install in the Play Store. If that doesn't work, you need to restore a factory image for your model S4.