Hi all. Sorry for resurrecting an old thread, but since all the information is here, I figured I would post here.
I DON'T CLAIM THIS FIX, ONLY SIMPLIFYING IT FOR THOSE WHO MAY HIT A SNAG AS I DID. Shouts out to KA52, SAMUELL.SK, ROBMAN2122. I apologize if I missed anyone else who contributed to this fix.
However, I ran into the same issue mentioned above, losing IMEI when flashing.
I am currently having an issue with my device (SNAIL W1/78P01) not connecting to 3G, and only 1 of the 2 AT&T supported 2G bands, which is 850. The device supports AT&T 850 and 1900 on 2G (Edge), and 1900 and 2100 on AT&T 3G.
Currently, I am only able to connect to 850 on 2G only. SIM works fine in other devices, and other SIM's exhibit the same issues when installed in my device.
After trying everything, I went for a FORMAT ALL REFLASH, which ended up with the above issue, losing IMEI and SERIAL NUMBER. Following the steps to get them back was more complicated than I thought, but I was successful. This post is to break down what was done. Note: It unfortunately DID NOT fix the issue with my mobile data. I can still only connect to 2G. If anyone has ideas, I'm opened to it, assuming I haven't tried it yet.
HOW TO RECOVER IMEI AND SERIAL NUMBER AFTER USING SP FLASH TOOL (FORMAT ALL+DOWNLOAD)
-- DOWNLOAD - 78Dian 5.6.27 for SP_Flash_Toolhttps://yadi.sk/d/d6tZwb8Zg3uuA
Snail A1 5.6.27 for SP_Flash_Toolhttps://yadi.sk/d/XtTyHoKyg3udW
-- COPY your NVRAM.bin to the folder with the update.
(NOTES) - If you MADE A COPY of your NVRAM in MTK DROID TOOLS. Navigate to the folder it is located in. There will be a BIN file and a TAR file. You will only need to copy the Bin File. Go to the update file you downloaded, and unzip the file. Copy your NVRAM.bin file into the folder.
-- OPEN FLASH TOOL and click SCATTER LOADING. Navigate to the update file you downloaded and added your NVRAM to. There should be only the scatter.txt file available. If not, then only choose the MT6592_Android_scatter.txt file.
-- You should see the Flashtool window populate with Green and White bars filled with information. Above them should be a Blue Title bar, unless you changed the theme. However, look for NAME, then look below it for NVRAM. Verify that there is a path to the file under LOCATION in the title bar. If not, click on the blank LOCATION BAR for NVRAM and navigate to the UPDATE folder you placed a copy of your NVRAM in and select it. The Path should then be populated for NVRAM in FLASHTOOL.
-- Make sure device is turned off completely and disconnected from the PC. Once confirmed, click DOWNLOAD.
-- Connect device to the PC via USB Cable and flashing will begin.
-- Once flashing has finished, you will see a GREEN CHECK showing completion.
-- Disconnect device from PC and power it up, while pressing the VOLUME DOWN repeatedly. You will enter the CHINESE recovery.
-- Navigate with the VOLUME keys, going down until you reach the option with EMMC in the Title. Select it with the POWER BUTTON.
-- The device will freeze for a moment, and then restart.
Hopefully I have helped someone.
If anyone sees something I missed or got wrong, please feel free to chime in.