[Android Q&A, Help & Troubleshooting] ndt44:
I have had no luck for nearly 2 years in rooting or installing custom recovery on my E6820 AT&T DuraForce Pro (which is soon to be retired as a GPS/Altimeter). I have already ordered a Ulefone Armor 6E as a replacement phone. I have attached below some partition info from my active, working E6820 in case anyone is still attempting to root these (this comes from an app called DiskInfo)

Some of the modules I'm guessing might be involved in locking the bootloader are:

*keymaster

*keymasterbak

*aboot

*abootbak

*boot

*keystore

======Partition info ======

--------------------------

Internal Storage

--------------------------

* zram0 [zram0] Not mounted

Total space: 512 MB

--------------------------

Internal Storage (MMC)

--------------------------

* modem [mmcblk0p1] (/firmware) [vfat]

Used: 83.1 MB, Free: 8.9 MB, Total space: 92 MB

* sbl1 [mmcblk0p2] Not mounted

Total space: 1 MB

* sbl1bak [mmcblk0p3] Not mounted

Total space: 1 MB

* rpm [mmcblk0p4] Not mounted

Total space: 512 KB

* rpmbak [mmcblk0p5] Not mounted

Total space: 512 KB

* tz [mmcblk0p6] Not mounted

Total space: 2 MB

* tzbak [mmcblk0p7] Not mounted

Total space: 2 MB

* cmnlib64 [mmcblk0p8] Not mounted

Total space: 512 KB

* cmnlib64bak [mmcblk0p9] Not mounted

Total space: 512 KB

* cmnlib [mmcblk0p10] Not mounted

Total space: 512 KB

* cmnlibbak [mmcblk0p11] Not mounted

Total space: 512 KB

* keymaster [mmcblk0p12] Not mounted

Total space: 512 KB

* keymasterbak [mmcblk0p13] Not mounted

Total space: 512 KB

* devcfg [mmcblk0p14] Not mounted

Total space: 512 KB

* devcfgbak [mmcblk0p15] Not mounted

Total space: 512 KB

* aboot [mmcblk0p16] Not mounted

Total space: 2 MB

* abootbak [mmcblk0p17] Not mounted

Total space: 2 MB

* boot [mmcblk0p18] Not mounted

Total space: 64 MB

* recovery [mmcblk0p19] Not mounted

Total space: 64 MB

* fota [mmcblk0p20] Not mounted

Total space: 64 MB

* fotabk [mmcblk0p21] Not mounted

Total space: 64 MB

* devparam [mmcblk0p22] Not mounted

Total space: 10 MB

* splash [mmcblk0p23] Not mounted

Total space: 25 MB

* reserve1 [mmcblk0p24] Not mounted

Total space: 512 KB

* reserve2 [mmcblk0p25] Not mounted

Total space: 512 KB

* system [mmcblk0p26] Not mounted

Total space: 4.5 GB

* Cache [mmcblk0p27] (/cache) [ext4]

Used: 89.9 MB, Free: 2 GB, Total space: 2.1 GB

* Data (userdata) [mmcblk0p28] (/data) [ext4]

Used: 18.7 GB, Free: 2.7 GB, Total space: 21.5 GB

* dsp [mmcblk0p29] (/dsp) [ext4]

Used: 8.2 MB, Free: 7.8 MB, Total space: 16 MB

* mdtp [mmcblk0p30] Not mounted

Total space: 32 MB

* devinfo [mmcblk0p31] Not mounted

Total space: 8 MB

* carrier [mmcblk0p32] (/carrier) [ext4]

Used: 5.5 MB, Free: 34.5 MB, Total space: 40 MB

* fotamng [mmcblk0p33] Not mounted

Total space: 257 MB

* reserve3 [mmcblk0p34] Not mounted

Total space: 56 MB

* reserve4 [mmcblk0p35] Not mounted

Total space: 2 MB

* reserve5 [mmcblk0p36] Not mounted

Total space: 2 MB

* fsc [mmcblk0p37] Not mounted

Total space: 512 KB

* ssd [mmcblk0p38] Not mounted

Total space: 512 KB

* DDR [mmcblk0p39] Not mounted

Total space: 512 KB

* fsg [mmcblk0p40] Not mounted

Total space: 2 MB

* misc [mmcblk0p41] Not mounted

Total space: 1 MB

* keystore [mmcblk0p42] Not mounted

Total space: 512 KB

* config [mmcblk0p43] Not mounted

Total space: 512 KB

* oem [mmcblk0p44] Not mounted

Total space: 64 MB

* limits [mmcblk0p45] Not mounted

Total space: 512 KB

* mota [mmcblk0p46] Not mounted

Total space: 512 KB

* reserve6 [mmcblk0p47] Not mounted

Total space: 512 KB

* dip [mmcblk0p48] Not mounted

Total space: 1 MB

* syscfg [mmcblk0p49] Not mounted

Total space: 512 KB

* mcfg [mmcblk0p50] Not mounted

Total space: 4 MB

* apdp [mmcblk0p51] Not mounted

Total space: 512 KB

* msadp [mmcblk0p52] Not mounted

Total space: 512 KB

* dpo [mmcblk0p53] Not mounted

Total space: 512 KB

* log [mmcblk0p54] Not mounted

Total space: 60 MB

* logwork [mmcblk0p55] Not mounted

Total space: 32 MB

* kcs [mmcblk0p56] (/kcs) [ext4]

Used: 9.5 MB, Free: 480 KB, Total space: 10 MB

* cslog [mmcblk0p57] Not mounted

Total space: 16 MB

* bootwork [mmcblk0p58] Not mounted

Total space: 16 MB

* sum [mmcblk0p59] Not mounted

Total space: 1 MB

* sec [mmcblk0p60] Not mounted

Total space: 512 KB

* chkcode [mmcblk0p61] Not mounted

Total space: 512 KB

* dnand [mmcblk0p62] Not mounted

Total space: 8 MB

* sysprop [mmcblk0p63] (/pstore) [ext4]

Used: 6.1 MB, Free: 1.9 MB, Total space: 8 MB

* persist [mmcblk0p64] (/persist) [ext4]

Used: 5.2 MB, Free: 10.8 MB, Total space: 16 MB

* modemst1 [mmcblk0p65] Not mounted

Total space: 2 MB

* modemst2 [mmcblk0p66] Not mounted

Total space: 2 MB

* bfss1 [mmcblk0p67] Not mounted

Total space: 4 MB

* bfss2 [mmcblk0p68] Not mounted

Total space: 8 MB

* reserve7 [mmcblk0p69] Not mounted

Total space: 7 MB

* kcs_work [mmcblk0p70] Not mounted

Total space: 1 MB

* mmcblk0rpmb [mmcblk0rpmb] Not mounted

Total space: 4 MB

--------------------------

SD Card

--------------------------

* android_meta [mmcblk1p1] Not mounted

Total space: 16 MB

* android_expand [mmcblk1p2] Not mounted

Total space: 14.8 GB

--------------------------

device-mapper

--------------------------

* System [dm-0] (/system) [ext4]

Used: 3.4 GB, Free: 1 GB, Total space: 4.5 GB

* dm-1 [dm-1] (/devparam) [ext4]

Used: 4.4 MB, Free: 5.5 MB, Total space: 9.9 MB

* dm-2 [dm-2] Not mounted

Total space: 21.5 GB

* dm-3 [dm-3] (/mnt/expand/hexSerialNo) [ext4]

Used: 11.3 GB, Free: 3.6 GB, Total space: 14.8 GB

--------------------------

tmpfs mount points

--------------------------

* /dev [tmpfs]

Used: 124 KB, Free: 890 MB, Total space: 890 MB

* /mnt [tmpfs]

Used: 0 B, Free: 890 MB, Total space: 890 MB

* /storage [tmpfs]

Used: 0 B, Free: 890 MB, Total space: 890 MB

* /storage/self [tmpfs]

Used: 0 B, Free: 890 MB, Total space: 890 MB

--------------------------

Memory

--------------------------

* RAM

Used: 1.3 GB, Free: 465 MB, Total space: 1.8 GB

* Swap

Used: 476 MB, Free: 35.5 MB, Total space: 511 MB