[G Pad 10.1 General] talvigi:
I have started it over again and i'm coming from CM 12.1 build date 17-11-2015 with nano gapps

As far as I am just following the OP, I will try keeping everything limited clean, and off course credit goes to the first person singular who started this post for all of us HE is the GURU here...

FIRST THINGS FIRST, I have already done this all twice before, so, things are quite similar to me and most of the job has previously been done i.e Downloading and Coping the needed files to SD card and placing the .kdz file in the concerned location, that is the folder of LG Flash Tool, OK, and most likely the major agent here ADB.exe ( I used “Minimal ADB and Fastboot” for this)

Since I was on factory firmware “Kitkat 4.4.2 V41010d” in my tab, and that was possible to be rooted, So, I used LGOneClickRoot for gaining root access and installed the Flashify app “com.cgollner.flashify_1.9.2-64_minAPI14(armeabi,armeabi-v7a,mips,x86)(nodpi).apk”

Than flashed “TWRP_2.8.5.0_v410_bumped.img” from the Flashify (searching the custom recovery inside my SDcard was a little time taking for me at first because, I used the Flashify builtin file browser) you can/may use the other way which is also available.

And another important/vital thing I did was to backup my current firmware “I checked all the options excluding External card and swipe to backup” (I think this is going to work for me some day when I want to goback official and someone may need to them too. Oh, dear, someone may be able to create a flashable .zip file from my source backup which is 100% factory firmware)

I rebooted to system and As I have always been doing, I finally checked for any OTA update from LG/ATT but nothing there,

Broken heated I finally decided to follow to the post to install CM 13 Marshmallow

To bring the tablet into Download Mode I powered it off, waited for about 15 seconds and hold the Volume Up button then plugged in the USB cable while holding the VolUP button down, and there we go to LG Download Mode. (my tab was unable to show the download screen (it showed up for the time till it says press the volume up button till download mode and it went off and never came back till the LG Flash Tool did its job).

I Ran LGFlashTool2014.exe. Selected the KDZ file (V41007h_0.kdz) and Clicked the "CSE Flash" button, Clicked "Start" (as the post said it should give me a window which should give option for choosing the language and region but language option was empty in my case, so I let it go leaving the consequences upon the software” And vola it started and showed progress both on the Laptop and Tab.

When all the things were done and my tab started for the first time, I was surprised to see all the thing same but the screen was showing

“userdebug”

4.20.17(42001700) (in Red words)

I again checked for an OTA update (as hope never dies) from settings menu > software update > update now BUT there it said (“Your tablet is not registered yet”) and following the OP I checked my device storage, contrary to the OP, Total space was 8 GB not 4 GB and the Available space was 3.54 GB (I don’t know why)

Now time for rooting again

I have had the LGOneclickroot installed and now running it for this step “Perfect job the device restarted when the One click root reached at 45% and it went off and now showing “Firmware Update” And it shows in the lower screen that the device is rooted. . LG One click root gave an error and went out.

Time to install Flashify and flash TWRP recovery (See above this step has been mentioned before)

a.	tap Flashify to install and it will ask you to allow unknown sources to install, just do it, because you have to believe us that we don’t try do any bad thing with your device

b.	After Flashify installs RUN it and tap flash TWRP

c.	Use the Flashify menu (in the right corner three dots) to reboot in to recovery

Here come the vertical lines for me, But I was not worried because I knew we had a fix to them, thanks to marcsoup's first post ever

From here Everything Copied from Original Post

(Yet I have tried to make things more concise, but our great Guru has made it so beautiful that I couldn’t make it better but removed some words which in my little opinion were not necessary because they made me more confused and in the last I came to know that I was unable to make things better, alas)

1.	Things get tricky here. As I have already copied parted (only because we only need file named parted inside the zip file) downloaded from here https://dl.dropboxusercontent.com/u/...-all-files.zip and ran "adb shell" from Minimal ADB and fastboot in the Windows to get a shell in TWRP.

(Shell in TWRP means you must be booted in TWRP recovery and your device should be connected to the PC/Laptop.

2.	In TWRP, unmount Data by tapping Mount > uncheck Data.

(In my case I had to reboot twice to TWRP Recovery just to Unmount the data partition) (And remember to recheck if you have really unmounted the data by going back to taping Mount and confirm the Data portion is unmarked and tap return)

3.	Now was time to copy and paste these commands in adb shell (I said copy and paste because I did so and recommend doing so because these commands are very very dangerous if mistyped. Working with parted. “Things really got tricky here but as far as our OP master has done everything so good try not to type if don’t you dare but if you do than your choice (I would suggest copy paste commands without apostrophies. Like this rm 33 and this cp /sdcard/parted /sbin/

4.	Typed this, without parenthesis {cp /sdcard/parted /sbin/}. This copies the parted binary to /sbin so it can be executed in the path.

5.	And now copied this {chmod +x /sbin/parted} To Make parted executable.

6.	And now {parted /dev/block/mmcblk0}(the last 0 is a ziro) this command will Run parted against the internal mmc.

7.	Now typed {p} this will Print the partition table.

8.	Now typed {rm 34} this Deleted the partition No. 34 labeled "grow".

9.	Now typed {rm 33} this Deleted the partition No. 33 named "userdata"

10.	And typed {p} this printed the partition table to confirm

11.	And now {mkpartfs} command to Create a partition and put a filesystem on it.

12.	And now it showed the following and I had to type words in parenthesis

name: {userdata}

type: {ext2 }

start: {3439MB} (the end of part 32. IT MAY BE DIFFERENT FOR YOU!) Don’t forget to Type MB after 3439 otherwise the offset will overwrite another critical partition (here I forgot to type MB after 3439 and had to do all the parted things again)

end: {15.8GB} (where "grow" ended above. IT MAY BE DIFFERENT FOR YOU!) Don’t forget to type GB after the 15.8 here too.

Typed {p} to Verify. For me it didn’t give a name to partition. Gotta fix that.

Typed {name 33 userdata}

Typed {p} to verify the last time.

In the last here, it’s not needed to flash Candy5 ROM to format data to ext4 format just remain in the TWRP and Run "adb shell".

Typed {mount | grep userdata} Make sure mmcblk0p33 is mounted

Typed {df} to Make sure /data is 11.3 GB (or whatever size it is on non-16GB devices) when I was going to flash CM 13 and by the way TWRP has the capability to format the data to ext4 partition format just ;

Tapped WIPE in the TWRP and tapped format DATA;

Tapped return and swiped to factory reset;

And now tapped install button in the TWRP chosen CM13.zip and Swiped to install

And tapped install button again to install opengapps micro and Swiped to install

And YES its done now tapped WIPE button and wipe devlock, cache etc, (I didn’t choose or select anything here Swiped after tapping the WIPE button and reboot to system.

Here I was in the Marshmallow world the system is now on 6.0.1 and updates every day.

Please press thanks button if i helped someone over there