[Droid RAZR M Q&A, Help & Troubleshooting] 5318008:
OK, if your Verizon Razr M is still on Jelly Bean, you've successfully performed this GMS hack, you're in the US on T-Mobile (maybe AT&T too? not sure), and you keep getting a 3G data icon but no actual data, these are the steps I took with my phone to fix that specific problem and get data to work properly. This is all assuming you already have RSD Lite and all relevant Motorola drivers installed, know how to get into AP Fastboot mode, etc.

1. Go to the Motorola Firmwares page, download the Blur_Version.183.46.10.XT907.Verizon.en.US and Blur_Version.98.30.1.XT907.Verizon.en.US ROMs, and extract them into separate folders.

2. Download and unzip the KK-RADIO-ONLY.xml and JB-RADIO-ONLY.xml attachments linked in this post. Put the KK one in the Blur_Version.183.46.10.XT907.Verizon.en.US folder, and the JB one in the Blur_Version.98.30.1.XT907.Verizon.en.US folder.

3. Boot your phone into AP Fastboot mode, hook it up to your computer, and run RSD Lite.

4. Run the KK-RADIO-ONLY.xml file. This will install just the radio from the KK ROM, and won't wipe any user data or anything. You can open up the .xml to check on it if you like. If it fails, you may have to try it again a couple of times, but it should go through eventually.

5. After your phone reboots, shut it down, boot it back into AP Fastboot mode again, hook it up to your computer again, and run RSD Lite again.

6. Run the JB-RADIO-ONLY.xml file. This will re-install the JB radio, won't wipe any user data, etc. If it fails, try it again, etc.

6. After your phone reboots, shut it down, boot it into Factory mode, and run the RadioComm GSM hack again.

Your phone's data *should* work properly now. A couple of notes on this fix:

If you keep the KK radio and do the GSM hack on it, it actually works pretty well, but it seems to break WiFi. I couldn't find any way to get WiFi working on JB with the KK radio, which is why I flashed back to the JB radio and noticed it was working fine afterwards.

I don't know what was causing my original issue, or why this fixed it. How the data seems to work on TMobile is, the icon sits at 3G when no data is being moved, then it switches to H+ when it actually needs data. In my case, it wouldn't switch over to H+ and I'd be stuck with no data.

The ROM my phone has is the Blur_Version.98.30.1.XT907.Verizon.en.US release of JB. If your phone is running one of the other JB releases, you may end up having to download your specific version. I'm not sure how much of a difference it'd make. You'd also have to change the appropriate lines the the corresponding JB .xml file that you'd use.

These .xml files were edited in Notepad++ so they should work fine. The code inside is the same, but they're not the actual copies I used when I flashed my phone, because those are back on my work computer.

I think I had a couple of other interesting notes to add but it's really late here and I forgot, sorry. I hope this helps someone out.

Edit: I remembered another note. For whatever reason, just reflashing the same radio I already had didn't fix my problem, nor did a complete reset or complete system reflash, only flashing to the KK radio and then back to the JB one.