After getting into some trouble with accidentally selecting USA Band in "Select Radio Band", I started to search for help on the forums and read a lot. Below you will find an easy way to unlock additional bands on your device or fix the issue of improper band selection.
Given that maybe nothing will happen to your warranty or there are small chances that your device might get bricked, I feel the need to say that I am not responsible for any damage caused by following these instructions. Any modification that you do to your phone you're doing at your OWN RISK.
The steps are quite easy to follow and the instructions are made for beginners and for those who don't know ADB commands (I am one). There are plenty guides out there I should say, but this one is adapted to our Le Max2 and I need to say that it WILL FIX the USA Band selection mistake that some might do
Lets pass to the instructions:
1. Make sure your phone is rooted and you have SuperSU installed, ADB drivers installed
2. Download "Setup DFS Studio" from http://cdmatool.com or the DFS Studio 16.05.31.0 (an older version) from here https://mega.nz/#!h1ImHJyK!gBcp2j6wI...YSoIjPkY_hJJVY
3. Connect the phone to the computer via USB
4. Select MTP and USB debugging
5. Open command prompt from Start => Run and type "cmd.exe". Once opened, type "adb shell". It should show "[email protected]_x2:/ $"
6. Open the SuperSU app on the phone
7. Type in cmd.exe "su" and grant access of ADB shell in SuperSU, you will see "[email protected]_x2:/ #"
8. Type in cmd.exe "setprop sys.usb.config diag,adb" and your phone will enter into Diagnotics Mode - this means that the MTP connection will be lost (you won't find any portable device in My Computer).
9. The drivers should be installed for the Diag Mode (in my case automatically - Win7 32bit) and you can see in Device Manager at Ports - Qualcomm HS-USB Android DIAG 901D (COMxx).
10. At this stage, if all should be well, you can start the "Qualcomm Tool" from DFS Studio folder. You can close the login window and it will run in demo mode (enough for what we need)
11. In the "Main" tab, double click on "Qualcomm HS-USB Android DIAG 901D (COMxx)" to select it - in the DFS log you will see "Qualcomm HS-USB Android DIAG 901D (COMxx) device in diagnostic mode"
12. In DFS Tool select tab "Band"
13. In tab "CDMA/GSM/HSPDA" select "RF BC Config" and then "Read"
14. Select the bands you need and then press "Write"
15. In the same tab, select "Bands Preffered" and do the same as above (read-write)
16. Select "LTE" tab which is aside "CDMA/GSM/HSPDA" and do the same as above. I changed values only in "LTE BC Config #6828" as the "LTE BC Config DIV #6829" didn't work for me when I pressed Read (there was nothing selected, all blank).
17. After operation had been completed, close Qualcomm Tool, unplug the phone and restart it.
1* At point 9 if the drivers do not automatically install, search for HTC DIAG DRVIER and change the .inf file and install them manually
2* To exit the diagnose mode, just unplug the phone from the computer and it will return to normal on the next connection. Kindly note that during the diagnose mode, the phone will be in "Charge only" state.
3* To make sure that the procedure is successful, do the steps once again and press only "Read" after the restart to see that the bands are indeed added.
4* This guide might be used for any Qualcomm device as long as it can be entered in diag mode.
5* To fix USA BAND Selection issue, it is necessary to select in "Band Preferred" the same bands as in "RF BC Config" and then write them.
6* Some might think that if they will select all bands, then the phone will work also on the Moon/ Mars. Well, that's not the case... I'm not sure what antennas are within the handset itself and if it will be able to work on different bands than specified by LeEco, but one might give it a try.
Original bands of the Le Max2
2G: GSM 2/3/5/8; CDMA (BC0 / BC1)
3G: WCDMA B1/2/5/8; TD-SCDMA: B34/39; CDMA (BC0 / BC1)
4G: FDD-LTE: B1/2/3/4/5/7/8/12/17/20/25/26; TDD-LTE:38/39/40/41
1. Will it work on my device? A: The tool is only intended to be used on Qualcomm devices, it won't work on Exynos, Mediatek, etc...
2. My device has a Qualcomm processor, can I unlock additional bands? A: In theory yes, but the hardware matters the most. This tool is just to unlock the software side.
3. I have unlocked band 20, why doesn't it work/connect to a network? A: As stated above, this depends upon the phone's hardware and antennas. Nobody can guarantee that if you'll unlock a specific band, then the modem will connect and operate on that band. The phone needs to have all the necessary hardware in order to operate properly but to only be limited on the software side - this is why we use this tool
4. What phones have been reported working until now? A: Why don't you give it a try and write down your feedback here?!
Credits for this goes to chatmonchy who actually gave me the idea to restore the preferred bands; the various guides for a lot of Qualcomm devices that can be found over the web; XDA community.