This has been a bit more involved than I was expecting:

Vol up + power for recovery

Install TWRP:

  adb reboot bootloader

  fastboot flash recovery twrp-3.2.3-2-beryllium.img

  fastboot boot twrp-3.2.3-2-beryllium.img

allow changes

Re-installing LineageOS

Wipe --> Advanced: Dalvik, Cache, System, data, Internal

adb reboot recovery # [need this for next step to work]

Wipe --> Format Data: yes # Sometimes I need to reboot and do this twice. No idea why.

adb sideload # Do I need this every time? Not risking not doing it.

adb reboot recovery # You never know!

adb sideload magisk

adb sideload

adb sideload

adb sideload # Optional, but you must do it before first boot.

adb reboot system

Older notes, probably not useful now

wipe --> advanced --> /data        --> format data   [ (system, data, cache) Wipe the data partition (or do a factory reset), Cache partition, Dalvik Cache or ART cache and Format the System partition. ]

  adb reboot recovery

mount --> cache, system, vendor, data

advanced --> adb sideload

  adb sideload DFE [ ]

  adb reboot recovery

Magisk (hides state of bootloader - might say locked)

  adb sideload magisk [ ]

vendor firmware

  adb sideload vendor-firmware [ from ]

wipe cache

  adb sideload DFE   <-- forgot this!

  adb sideload los [ ]

GApps if wanted [ Open GApps ]


clear cache

reboot system

NEED TO re-flash DFE every time I flash a ROM or /vendor (actually just vendor but ROMs sometimes write to /vendor themselves, so it's safer) or I risk getting stuck in a bootloop or losing data.


  • [2G] GSM 900
  • [2G] GSM 1800
  • [3G] UMTS band 1/8
  • [4G] LTE band 1/3/7/8/20/38/40
In LineageOS these equate to GSM/WCDMA/LTE under Network & Internet --> Mobile network --> Advanced --> Preferred network type

In the UK, I believe these are the bands that are used:

  • O2 (GSM, WCDMA)
  • Vodafone (GSM, WCDMA)
  • 3 (GSM, WCDMA, LTE band 3 only)

Camera - port of MIUI 10 camera


[FIX] How to solve "unable to mount data" error

1,618 posts
Thanks: 1,457
By Phil_Smith, Senior Member on 29th March 2018, 07:39 PM

recently many are facing the problem to suddenly receive the above error and aren't able to solve it by formatting data (well, it cannot be mounted).

Here are the steps that I suggest in case you find yourself in that situation (obviously all data including internal storage content will be gone afterwards, so make external backups of important stuff if you can before continuing)

- (re-)flash lastest twrp (currently via fastboot
- boot to recovery
- wipe dalvik, cache, vendor, system, data
- format data (the one where you need to type "yes")
- reboot to recovery before flashing anything
- now flash your stuff