upgrade to Android 10 OTA with unlocked bootloader - Nokia 7.2 Questions & Answers

Hi guys,
i hope you can help me a little. This phone drives me crazy.
The goal: Android 10 OTA with TWRP
What i did so far:
bought the downgrade firmware to v1.200 with techmesto
bootloader unlocked
flashed TWRP 3.3.1.0 via fastboot flash boot *.img
WIFI can not be activated on v1.200 firmware
( Update on 2020.11.22: Wifi only works if the montly timestamp of the rom security patch level is the same of the TWRP time stamp)
thats why OTA update via APP is not possible
because of that, i tryed to adb sideload via TWRP the OTA firmware v1.390 FULL OTA from telegram "Nokia OTA Repository" ( i know 390 is android9. It should be just the first step)
I did this on A
reboot
firmware is still v1.200 (WTF?)
got the information via telegram to change the slot, done via TWRP, switched to B
reboot
phone is booting to default recovery and saying "...00WW_1_390" ... "can't load android system. your data may be corrupt"
flashed TWRP 3.3.1.0 via fastboot flash boot *.img on B (i guess)
my phone is now booting to TWRP only
boot to TWRP and restored full backup of v1.200
Result: my phone is now booting to TWRP only, no matter i activate A or B in TWRP. What can i do?
Is it possible to flash the Nokia OTA Repositorys via TWRP?
Best,

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Hi, you should not flash TWRP on the device except for if you want to flash a custom ROM. Due to the way TWRP for this model is developed, your WiFi will not work if you flash the TWRP image to you boot slot. Basically the same if you flash any modified boot image.
Also, since the boot image is what is responsible for getting your device to boot to the system, flashing a TWRP to boot slot can also result in the device not booting at all and instead getting stuck with TWRP only.
What I recommend:
Load TWRP, flash any full OTA (Android 9 or 10)
Do a full wipe (factory reset equivalent - essentially erase userdata) and then change the slot (if current is B, change to A). And finally reboot.
Good if the device boots up.
If not, please use NFT to flash any full OTA update you'll find in the Telegram channel (Android 10 preffered). That should get your device to boot normally
The culprit for your non-working WiFi is not the 1200 firmware, but the fact that you flashed the TWRP image to your boot slot I hope that helps

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singhnsk said:
...What I recommend:
Load TWRP, flash any full OTA (Android 9 or 10)
Do a full wipe (factory reset equivalent - essentially erase userdata) and then change the slot (if current is B, change to A). And finally reboot. ...
Click to expand...
Click to collapse
This worked very well. ( before and after i did a normal wipe in twrp). After installing v1390, I did the factory reset not in twrp but , after a reboot, in the default recovery. And the phone now boots again to android.
Thank you very much.
So to sumarize: After flashing an OTA with TWRP or adb sideload it is very important to "... then change the slot (if current is B, change to A)"

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Android v1.390 wants to install an update 1510MB in size , directly at the first start assistant. There is no option to proceed without that direct update.
Is it possible to loose my unlocked bootloader with this update?

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Aha.. Yeah, if you reset the device while OEM Unlocking is not enabled in the Settings (which disables device protection features) and a Google account was added, then the phone will trigger FRP lock which will force you to connect to a WiFi network before you can get into the phone. And such WiFi will then force you to update the phone before you can start to use it.
You can update though. It is okay. It won't affect an already unlocked bootloader. The bootloader will remain unlocked ?

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thanks, yeah, nearly all done on my phone now.
But .... the default recovery doesn't work. After selecting "recovery mode" in fastboot mode i get a dead android. Can i fix this some how ?
{
"lightbox_close": "Close",
"lightbox_next": "Next",
"lightbox_previous": "Previous",
"lightbox_error": "The requested content cannot be loaded. Please try again later.",
"lightbox_start_slideshow": "Start slideshow",
"lightbox_stop_slideshow": "Stop slideshow",
"lightbox_full_screen": "Full screen",
"lightbox_thumbnails": "Thumbnails",
"lightbox_download": "Download",
"lightbox_share": "Share",
"lightbox_zoom": "Zoom",
"lightbox_new_window": "New window",
"lightbox_toggle_sidebar": "Toggle sidebar"
}
UPDATE: i found the solution to enter the recovery mode after seeing the dead andorid no command screen:
"You have to press and hold the power button. Now press and release the volume up button but continue to hold power button"
After that i could enter the recovery mode.