Oukitel WP15 bootloop (maybe bricked) - Android Q&A, Help & Troubleshooting

Hello,
I'm going on again on my WP15 which is on bootloop after trying to put an magisk patched rom to obtain root.
The objective now is just to put a official factory rom (which I downloaded from the official website for the right model)
The problem now is not how to do that but how I can connect the phone to the computer because :
Assuming that the phone is connected via usb-c to the computer on usb-a and the phone is on.
1 The screen is black
2 windows connect sound
2.1 Com port connected (device manager)
X wait 1s
3 windows disconnect sound
3.1 com port disconnected (device manager)
2&3 x2
4 Screen on : On screen :5G oukitel logo + android logo + Orange state; devive unlocked[...] not trusted[...]; device will boot on 5s
repeat 1 indefinitely
Please Note :
That I do not have ADB access since I switched from w10 to 11 so the rsa keys are not valid.
The phone is stuck but when I say stuck, it's completely because button vol- + power = nothing, constant bootlooping and vol+ + power = the same schema (1,2,3,4) except that there is no wait time between 2 and 3, it's instant.
The phone is only off when out of battery, As soon as I connect a cable the phone turn on and I can do nothing except disconnect cable and wait (Can be very long with an 15000 mAh battery...)
There is absolutely no custom bootloader so no twrp or any custom recovery/installation bootloader.
With that... I think it's definitely bricked... I'm already thinking of soldering a new rom (or asking someone to do for me)
If you need more details or precisions tell me !
Thank you in advance !

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Lunalunea said:
The phone is stuck but when I say stuck, it's completely because button vol- + power = nothing, constant bootlooping and vol+ + power = the same schema (1,2,3,4) except that there is no wait time between 2 and 3, it's instant.
Click to expand...
Click to collapse
seems you missed the most important thing what I've said - ignore any phone activity, just hold.
use this for flashing https://spflashtools.com/windows/sp-flash-tool-v5-2208 I've used 5.2134, lower versions not support mtk6833. and do not use 6.+ versions.
again:
- install mtk usb-com drivers (by manual of flashtool if you did not do it yet)
- check at firts only boot.img and vbmeta.img (do not use "format" only "download")
- power off phone (if you can't, plug your phone in pc and click "download", it'll throw error with suggestion to disconnect battery, but phone would power off. if this didn't help, then just skip this point and try to continue anyway)
- unplug your phone
- click "download" button (yes while your phone unplugged)
- on unplugged phone, hold both volume buttons and hold power button too (three buttons at once).
- hold it all >15 seconds (20 for sure) and ignore any phone activity, just hold.
- release power button only (keep holding both volumes)
- plug your phone (still keep holding both volumes)
- now flashing process must start and you may release any buttons.

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vxsw said:
seems you missed the most important thing what I've said - ignore any phone activity, just hold.
use this for flashing https://spflashtools.com/windows/sp-flash-tool-v5-2208 I've used 5.2134, lower versions not support mtk6833. and do not use 6.+ versions.
again:
- install mtk usb-com drivers (by manual of flashtool if you did not do it yet)
- check at firts only boot.img and vbmeta.img (do not use "format" only "download")
- power off phone (if you can't, plug your phone in pc and click "download", it'll throw error with suggestion to disconnect battery, but phone would power off. if this didn't help, then just skip this point and try to continue anyway)
- unplug your phone
- click "download" button (yes while your phone unplugged)
- on unplugged phone, hold both volume buttons and hold power button too (three buttons at once).
- hold it all >15 seconds (20 for sure) and ignore any phone activity, just hold.
- release power button only (keep holding both volumes)
- plug your phone (still keep holding both volumes)
- now flashing process must start and you may release any buttons.
Click to expand...
Click to collapse
Hello,
Sorry, I was not very active since this post and I abandoned for a very long time.
But ! Your instructions was good and I finally got my phone back to life !
Since then I realized that the Oukitel brand is very sketchy about theirs ROMs on the Oukitel website because the WP15 model is associated with the WP13 ROM on the download center so... WHY ? this is so confusing because now I have a WP15 advertised ROM (From a website... Yes... I know I was dumb to do that) and it's working yes... but this is very buggy for example the gyroscope is crazy or my MAC address is never the same even if I turn the built-in MAC address spoofing option off...
I will do some research just to get my phone as normal by doing it as clean as possible because I know now what is implying for doing that.
Thank you so much for your patience and especially for your guide and I apologize for my dumbness.

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Lunalunea said:
the WP15 model is associated with the WP13 ROM on the download center
Click to expand...
Click to collapse
have no idea what are you talking about.
just checked in dl center on oukitel official site and seems all is ok. wp15 have it's own fw page and redirect to correct dl fw page, wp13 have it's own.
you can't mix up fw, in case wp13 signed exactly as wp13:
v318a-oq-s88-128g8g-bom2-hdp-r0-cts-eu_OUKITEL_WP13_EEA_V12_20210731_user_20210731.tar .gz
wp15 have no direct sign, but it have a cpu defenition:
TF919_OQ_S89_6833_R0_EEA_V1.9.7.2_S211014 .zip
i.e. mt6833 aka dimensity 700. wp 13 have a dimensity 800 aka mt6873
nb, in dl center, fw tool seems not works properly, so you must use a flashtool as I'd referred before.

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I've tried everything, for 5 full days, then had no option left but to give up. Sorry.