[OnePlus 8 Guides, News, & Discussion] sbpetrack:
EDIT: I am up and running, thanks!! It seems that the "fastboot rom" just includes a bat file to automate the fastboot commands (under windows). And if anyone is confused about how to get a powered-off OnePlus 8 into fastboot: what worked for me was holding BOTH Volume UP AND Volume Down, THEN pressing PowerOn.

Still open questions:

1. if i should upload here the 11.0.7.7.IN21AA (Global) rom I have, let me know

2. Now that I successfully flashed slot A, should I also then flash slot b? or does android take care of this itself.

again, thanks

Two (perhaps) related things, one "offer" and one "desperate close-to-noob plea for help"

Context for both:

1. I have/had a rooted OnePlus 8 with unlocked bootloader that was running 11.0.5.5.IN21AA (Global). My phone told me to upgrade to 11.0.7.7 via OTA, and I thought I could do this safely without trouble. From what I could see, I knew that I would lose root, but that's ok, my plan was just to repatch the new boot.img via Magisk and reinstall Magisk after the upgrade.

2. After the upgrade, there was left on my phone the following file:

OnePlus8Oxygen_15.I.37_OTA_0370_all_2106020022_653a6a893088d.zip

I extracted the boot.img from this, patched it via Magisk, flashed it from a PC via "fastboot flash boot patched_boot.img", rebooted, and thought I had finished what I meant to do.

*****

QUESTION/OFFER: is this file of use to anyone? I see that it is not quite the same name as the one posted in the previous post. Should I upload it or give someone a link to it? Just trying to be helpful.

EDIT: I believe/assume that my .zip file is for an IN21AA (Global) phone, while the previous post has a European (BA) ROM. So please let me know if it is useful for me to upload somewhere

*****

3. Unfortunately, Wifi no longer worked and i could not make or receive phone calls. In the end, I tried a factory reset, and as a result, my phone seems to be in a bootloop. To be as precise as I can be:

I see the OnePlus 8 "big red dot" and the two little white satellite dots that go round and round. After a while, the two white dots become one and drop into the red dot, like they're supposed to. But then:

sometimes the screen just goes black, and after a while, i see the big red dot and it repeats; but

sometimes the screen just goes black, and after a while, I "SAFE MODE" at the bottom left. but then after a while that "SAFE MODE" disappears and I get the big red dot again; and

very occasionally I get a choice to "restart" or "power off". If I do nothing and try to decide which I should choose -- the screen goes black and I get the big red dot again.

Which one happens MIGHT be related to the combinations of power and vol +/- that I'm trying... I see contradictory advice all over about what I should do.

The last time I got the "restart/power off" choice, i quickly chose Power Off -- and amazingly, the f***ing thing turned off!!!

QUESTIONS:

1. CAN SOMEONE PLEASE PLEASE PLEASE point me to the CORRECT instructions for what I do to restore stock firmware?

2. And is the file I saved from the upgrade OK, or should I download the one posted in the previous post?

3. I note that the instructions I see that use fastboot tell me that I need a "fastboot rom" -- and both the one posted above and the one I have seem to be an OTA rom and not a fast boot rom. DO I care? If it's relevant, I had absolutely no trouble to use payload_dumper and successfully extracted 35 different .img files, which i now have on my PC.

But my phone is now OFF, if i look online, i find THREE contradictory instructions even just for what key combination to use to get the thing into fastboot mode. Why are people such d***heads and post stuff that is clearly just false info? I feel like I can trust the info I might get here.

My profound apologies for being so ignorant. I'm sure this must be the 10000th time someone has asked something so stupid. It's just that searching gets me completely inconsistent answers. If it helps, I will be happy to post here the actual correct instructions for my OnePlus 8 (including all details, such as key-combo for fastboot mode, and whether one can use an "OTA rom" with fastboot etc.

let me know if I should post my ROM .zip file somewhere (attach it to a post here, for example)