[General Questions and Answers] Android#:
Just an update, while trying to make a 'read back' dump using sp flash tool, I accidentally started a download of the FTJ152D MM firmware I was using the scatter file from... Needless to say now I have the demo version of marshmallow and have lost my IMEI info from phone. I did make a 'read back' dump of the phone before i messed up, using the guide from syserr about "Dump Full Rom" at

https://xdaforums.com/showthread.php?t=2540400.

NOTE: If you are still on stock rom that the phone shipped with, DO NOT try upgrade using SP flash tool, at the very least you will loose IMEI information for both sim slots. For me, the phone connects with sim but I can only get 2g data speeds and make phone calls.

I am hoping that the following information can help others:

1) Most Important: If you root, do not use SUPERSU 2.79 or above versions or phone will be stuck in bootloader. Even if you make a backup of boot.img, sideloading it from ADB did not work for me, it kept failing. I am not sure if earlier SuperSU versions work or not, if they do work, make sure you disable auto update for SuperSU in Google Play Store.

2) Even if you make a backup of nvram.bin using sp flashtool, it will NOT restore your imei information in the phone because from what I researched so far, this information is populated using the BPLG and AP databases that are included with the stock firmware as separate files and quite possibly with 64-bit mtk processors, this information is protected and encrypted. Other possibility is that the nvram.bin i recovered from my whole rom dump is for lollipop and since phone is running on marshmallow, this bin file is invalid? I did try flashing two different nvram.bin (one i recovered from the stock dump i made when phone worked, another i downloaded from internet) using flashtool and it made the matters worse, all baseband info disappeared and both sim slots just totally greyed out in settings. If it greys out for you, just format the whole flash and flash the MM firmware again without any nvram partition. Just leave default settings for nvram in scatter file alone.

3) Currently, there is no way to root this phone when on marshmallow. Do not try the chinese one-click or other software such as miracle box, all the ones i downloaded and/or tried or not tried, were flagged by Anti-Virus as trojans and viruses.

4) Be very careful when trying to flash software on this phone, make sure you use the correct Preloader.bin file. The marshmallow firmware on needrom website has a preloader.bin file in it and it works fine. Do not attempt to try preloader from other similar phones or you will brick this phone permanently.

5) ADB and Fastboot commands do not help because the phone is not rooted anymore once you upgrade to marshmallow using the FTJ152D marshmallow firmware from needrom.

6) I have tried combinations of boot.img, and system.img from Priori 3 (it is also dual sim and rom on needrom website is android 5.1), was hoping for a miracle but no luck.

7) MTK Droid Tools works partially with this phone. Most options in the tool require root or do not work with mt67xx processors. I found mtk droid tools useful to enter recovery directly when usb debugging was enabled or to go to ADB terminal to try sideload or reboot bootloader to enter fastboot.

8) Even if you enable oem unlock in developers, the option (volume+up) in Fastboot menu to unlock the bootloader doesn't work. It seems that many MTK processors have this option disabled by the manufacturer.

9) TWRP custom recovery will not work with this phone because the 'boot script' (not bootloader) before actual recovery in the recovery partition has the touch disabled. I was able to get CWM to work by directly flashing it instead of stock recovery but installation of any zip files through recovery fail still.

10) I can confirm that the scatter file in marshmallow rom for FTJ152D available at needrom website has the right entries and address locations for our phone (FTU152D) because I was able to use that scatter file and a Hex Editor program (search for HxD on download.cnet.com) to carve out almost all the partitions from the 2gig partial rom dump I had of my phone in working state. When carving partitions from the dump, some trimming for certain folders is required because cutting the partition by size and making it a .bin or .image file will give errors in SP Flash Tool otherwise. The marshmallow rom or a Priori 3 lollipop rom, both can be used as a reference when cutting out the extra bytes.

If you are like me and have upgraded to marshmallow using the FTJ152D software, there are not many options. I haven't given up yet though, I backtracked my steps trying to make a backup of the phone in its current state using SP Flash Tool full rom dump and it was successful. If I could get my hands on full rom dump of 5 gigabytes of a working phone with lollipop software, I am confident I can restore my phone back to lollipop. This may not fix the IMEI problem but once the phone is running lollipop, it is possible to root it again using kingroot or towelroot and then use one of the imei repair apps or a program to rebuild nvram folder using the BPLG and AP databases and use root explorer to place it in the phone.

Phew... a long write but hope this helps others, and if anyone can help by sharing any thoughts or uploading their stock rom dump if own same phone (can read syserr's method of using 'read back' in SP flash tool to make one big partition dump for the whole rom instead of making seperate partitions which is a painstaking process.