[AT&T, Rogers, Bell, Telus Samsung Galaxy S III] Opie Knievel:
I recently lost my IMEI and didn't have a backup. Stupid move on my part. Now I know I need to do a backup before flashing ROMs. Anyways, I just got off the phone with AT&T and I will have a replacement here in 2-3 days. As I'm sure most of you know I'll have 10 days to send my old one back. Before I return it to stock and send it back I am willing to help in the research of this problem and a potential solution. I have done a lot of searching on this forum and I haven't found a solid solution. If anyone has some theories they would like to try you have a few days to let me know and I'll see if I can be of help.

Here is the history of the phone as best I can remember:

-Bought brand new December 7, 2012

-Updated to Jelly Bean 4.1.1 through Kies. No noticeable problems

-Rooted with Odin v3.04 Team Epic Root from Recovery with CWM v5.0.4 and Super User I kept the stock ROM for awhile before flashing anything else (Made a Nandroid of this ROM) No noticeable problems.

-Flashed Drew Garen's Serenity 1.2 No noticeable problems

-Flashed Pure Motive's Galaxy Mod Rls 14.1 No noticeable problems

-Flashed Pure Motive's Galaxy Mod Rls15 (This is where the problems began) Did a full wipe (data, cache, dalvik) like I always did. Rebooted after flash and noticed that my service sucked and my data wouldn't connect. I checked the APN's and they were wrong. Changed the APN's and the data would connect but I still had poor service. The phone wouldn't even make a call. It took me a little while to figure out that the IMEI was missing. It just read 0. After some searching I found a method of injecting the IMEI: http://xdaforums.com/showthread.php?t=1804117 I used this method and put the original IMEI back in. Of course that didn't fix my data or poor service issues.

-Then I tried Peoplearmy's method: http://xdaforums.com/showthread.php?t=1801997 Actually I only did the make a backup part with QPST. I couldn't use the QCN Generator app because I only had Windows XP and the app requires Windows 7.

-I flashed my Nandroid backup. No help.

-Flashed Stock Jelly Bean I747UCDLK3. No help.

-Rooted the phone again, using the same method as above.

-At this point I became desperate (stupid) and tried a method for the GT-i9300: http://xdaforums.com/showthread.php?p=30773406 This definitely didn't work and now I lost my serial number.

-Last night: Finally got access to a Windows 7 computer. Tried The SGS3 QCN Generator app. This time it worked and made a QCN. I injected it into the phone. No help. The QCN data I used was from after I lost IMEI and had manually put it in. I'm not sure if this is part of the problem of why it didn't work or not. The way I understood things it was supposed to repair the other parts of the QCN data. Someone please correct me if I'm wrong.

-I actually made an EFS backup on Galaxy Mod Rls14.1 using the Aroma installer. From what I've read this wouldn't necessarily help anyways because it doesn't contain all of the data needed to do a complete backup which is kind of beside the point because it's in tar format not in zip and it's a tiny file. 58 Bytes.

-I have installed Root Explorer and looked in the EFS folder and it doesn't contain any nv_data files.

I have already installed Triangle Away and cleared my flash counter.

So, if anybody who actually knows what they're doing (cause I obviously don't) would like to help, especially if my situation can be used to fix/prevent this from happening, and wants to use me and my I747 as a Guinea Pig let me know.

-Right as I was getting ready to post this I scrolled through settings>about device>status, and my correct Serial Number was back. What the ....? The only thing I've done to the phone is toggle airplane mode a few times, turn it off and on a few times, used wifi to get online, pulled the battery, booted up in CWM recovery. I haven't flashed anything to the phone. This is odd. Any help or feedback would be greatly appreciated.