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Phone Maker: TECNO Model: F1 OS: Android 8.1 (Go Edition) Memory: 8GB ROM 1GB RAM

I have asked a question here: Android fastboot restoration points

In summary the phone was updating then the battery died and now it is stuck in fastboot mode. It shows the text => FASTBOOT mode... in the bottom left corner of the fully black screen.

I discovered its possibly a single slot device (does NOT support seamless system updates) and obviously the update process got bad. What are the ways to recover from this (fastboot mode screen) so the phone boots up correctly. I am currently using ADB, Fastboot to interact with the phone via USB. Below is the output that I get when I run 'fastboot getvar all' on a windows 10 system.

(bootloader)    max-download-size: 0x8000000
(bootloader)    partition-size:flashinfo: 1000000
(bootloader)    partition-type:flashinfo: raw data
(bootloader)    partition-size:userdata: 14ff80000
(bootloader)    partition-type:userdata: f2fs
(bootloader)    partition-size:cache: 7000000
(bootloader)    partition-type:cache: ext4
(bootloader)    partition-size:system: 59000000
(bootloader)    partition-type:system: ext4
(bootloader)    partition-size:keystore: 800000
(bootloader)    partition-type:keystore: raw data
(bootloader)    partition-size:secro: 600000
(bootloader)    partition-type:secro: raw data
(bootloader)    partition-size:oemkeystore: 200000
(bootloader)    partition-type:oemkeystore: raw data
(bootloader)    partition-size:metadata: 2500000
(bootloader)    partition-type:metadata: raw data
(bootloader)    partition-size:nvdata: 2000000
(bootloader)    partition-type:nvdata: ext4
(bootloader)    partition-size:tee2: 500000
(bootloader)    partition-type:tee2: raw data
(bootloader)    partition-size:tee1: 500000
(bootloader)    partition-type:tee1: raw data
(bootloader)    partition-size:frp: 100000
(bootloader)    partition-type:frp: raw data
(bootloader)    partition-size:vendor: 12000000
(bootloader)    partition-type:vendor: ext4
(bootloader)    partition-size:expdb: a00000
(bootloader)    partition-type:expdb: raw data
(bootloader)    partition-size:odmdtbo: 1000000
(bootloader)    partition-type:odmdtbo: raw data
(bootloader)    partition-size:logo: 800000
(bootloader)    partition-type:logo: raw data
(bootloader)    partition-size:para: 80000
(bootloader)    partition-type:para: raw data
(bootloader)    partition-size:recovery: 1000000
(bootloader)    partition-type:recovery: raw data
(bootloader)    partition-size:boot: 1000000
(bootloader)    partition-type:boot: raw data
(bootloader)    partition-size:lk2: 60000
(bootloader)    partition-type:lk2: raw data
(bootloader)    partition-size:lk: 60000
(bootloader)    partition-type:lk: raw data
(bootloader)    partition-size:seccfg: 40000
(bootloader)    partition-type:seccfg: raw data
(bootloader)    partition-size:persist: 3000000
(bootloader)    partition-type:persist: ext4
(bootloader)    partition-size:protect2: a00000
(bootloader)    partition-type:protect2: ext4
(bootloader)    partition-size:protect1: a00000
(bootloader)    partition-type:protect1: ext4
(bootloader)    partition-size:nvram: 500000
(bootloader)    partition-type:nvram: raw data
(bootloader)    partition-size:proinfo: 300000
(bootloader)    partition-type:proinfo: raw data
(bootloader)    partition-size:preloader: 40000
(bootloader)    partition-type:preloader: raw data
(bootloader)    off-mode-charge: 1
(bootloader)    warranty: yes
(bootloader)    unlocked: no
(bootloader)    secure: yes
(bootloader)    kernel: lk
(bootloader)    product: K80_BSP
(bootloader)    version-preloader: 0.1.00
(bootloader)    version: 0.5
all: Done!!
Finished. Total time: 0.142s

I tried the command fastboot reboot recovery but it responds ok and still displays the fastboot mode text

How can I: 1.) Recover the data by booting into the recovery partition (right now I am unable to access the recovery partition) 2.) Recover the data and boot the device via other means apart from recovery partition

Flashing the phone is a last resort. But is it possible to Flash the phone and still retain the data I had on it before this incident occured?

PS: For obvious security reasons I only intend to stick with official tools (ADB, Fastboot) to solve this problem. I am NOT willing to install any unofficial software on my computer.

thinkhjj
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  • @alecxs I intentionally removed the actual values and replaced them with xxx. It shows actual values I am able to see it in the command line output. When I use key combos I am able to get into recovery mode. But I do not want to do a factory reset, at least NOT yet. – thinkhjj Aug 08 '20 at 10:56
  • fastboot reboot recovery is a command I have seen in the xda forums while researching into this matter – thinkhjj Aug 08 '20 at 10:57
  • @alecxs I have modified the question above. been doing some research and found its possible to flash the stock rom via fastboot. – thinkhjj Aug 08 '20 at 23:58
  • fastboot is disabled (bootloader) unlocked: no therefore your only hope is SP Flash Tool. in your case most likely only system.img must be flashed, and cache partition should be cleared. in any case your personal data is on userdata + metadata partition and should be backed up with valid scatter file (just to keep it safe) – alecxs Aug 09 '20 at 08:24
  • scatter does not fit scatter file. you must create scatter file for your own. Do a "read back" of your phone. in SP Flash Tool select DA_SWSEC.bin as Download-Agent (source). you can follow below instructions afterwards – alecxs Aug 09 '20 at 09:02
  • please note there is no official site for SP Flash Tool, but the tool itself is. however, the software provided by it's origin sources spflashtools.com and 4pda.ru (registration required) can be trusted – alecxs Aug 09 '20 at 09:18
  • The plan is to unlock the bootloader to allow me flash the stock rom. Hopefully the phone will allow me to unlock the bootloader using the fastboot oem unlock (not tried yet). Then I can download the ROM for the phone then flash it. Do I need to wipe my phone first before flashing? I intend to keep my data. – thinkhjj Aug 09 '20 at 14:37
  • i have checked the scatter file provided by theggputest55 as you can see the discrepancy is for userdata partition (type ext4 vs f2fs) size 1.5 vs 5.25 GiB https://pastebin.com/upMT5X1v so you can use that scatter for flashing system but you can't use it for backup userdata – alecxs Aug 09 '20 at 16:02
  • thanks for all the useful input. So in the current state the phone is in how do I backup the contents (all partitions)? Then I can flash using you suggested method then restore when the flashing is successful. – thinkhjj Aug 12 '20 at 11:34
  • update the scatter file with proper partition size (0x14ff80000) for userdata (or create new one), backup partitions from "read back" – alecxs Aug 12 '20 at 11:40
  • https://android.stackexchange.com/q/220584 – alecxs Aug 13 '20 at 00:14
  • @alecxs , Thanks a lot for all of the feedback. I have obtained SPFlashTool using the link provided. Questions: 1)How do I create a scatter file for my device?(is it possible with SPFlashTool or can it be done via command line?)Now I know scatter file is basically a .txt file how do I get it from my device with SPFlashTool? 2)When I have the scatter file how do I use it to make a backup of my partitions? 3)Now when I want to flash the ROM, it is this same scatter file that I will use in SPFlashTool yes? – thinkhjj Oct 25 '20 at 16:30
  • download some similar scatter file and change the values with wordpad 2) you can't straight use the scatter file for readback but you can create readback entries with that values 3) yes, except the ROM requires repartitioning (not recommended)
    • – alecxs Oct 25 '20 at 19:34
  • it is important first to install VCOM preloader driver. the phones preloader is detected only for first ~1-2 sec when connecting, and only when phone is powered off. Therefore you must click start readback as 1st step and connect usb cable as 2nd step, readback will start immediately as soon as preloader is detected. Tutorial step 5 (skip step 1-4) – alecxs Oct 26 '20 at 07:57