[OnePlus 6T  Questions & Answers] deathtothespy:
Hi guys, I've been using the 6T for a while and it had been working fine, it just had some weird issue where the battery didn't last very long, sometimes it didn't even make it past 3 hours SOT.

It was weird because it had maybe 5 bad days and then it would jump to 4, maybe 5 hours SOT. It was a bit of a hassle but I didn't really care.

Then, one day, the phone was plugged in and charging and I got an important email. I picked up the phone, unplugged the charging cable and suddenly the screen turned off. I hold the power button and it started booting, and when it was at the OxygenOS animation with the two spinning circles, it froze.

The phone was in Android 10, the second OxygenOS update, if I'm not mistaken. Since then, I've tried everything I could:

I have tried to let it rest for a couple weeks and try powering on again, it keeps freezing at the boot animation.

I tried using MSMDownloadTool to flash older Android versions with no success, as it kept freezing on the first boot after flashing.

The only advancement I've made was when I flashed HydrogenOS, the phone kept freezing, and then I flashed OxygenOS 9, as the animation kept spinning longer until freezing.

To this day (02/24/2020), almost a month and a half after I had the first accidental shutdown, I haven't been able to boot the phone.

I don't have warranty of any kind, as I chatted with OnePlus and they told me my warranty had already expired.

At the beginning I thought it could be some kind of motherboard failure, but I disassembled the phone and didn't see anything that could confirm that.

After flashing back Oxygen and seeing that it hold much longer the boot process, I started thinking it could be some kind of software failure. But since my phone wasn't bootloader unlocked, and it isn't possible to unlock if ADB debugging isn't enabled, I think I'm pretty much screwed.

I have tinkered a bit with fastboot and I was able to extract this information:

(bootloader) has-slot:modem:yes
(bootloader) has-slot:system:yes
(bootloader) current-slot:a
(bootloader) has-slot:boot:yes
(bootloader) slot-retry-count:b:0
(bootloader) slot-unbootable:b:no
(bootloader) slot-successful:b:no
(bootloader) slot-retry-count:a:6
(bootloader) slot-unbootable:a:no
(bootloader) slot-successful:a:yes
(bootloader) slot-count:2
(bootloader) secure:yes
(bootloader) product:sdm845
(bootloader) max-download-size:536870912
(bootloader) kernel:uefi

from which I understand the following:

the phone appears to have a working system, which I'm not 100% sure of. I read this from

(bootloader) slot-unbootable:a:no
(bootloader) slot-successful:a:yes

. And the phone keeps trying to boot:

(bootloader) slot-retry-count:a:6

.

So, I have no idea what to do now. I loved this phone and it has been the best phone I've ever had the chance to have. I don't want to leave it into a drawer. It looks like it could still be revived, but I no longer know what to do. I thought of building a custom system image with adb debugging and the system logger enabled to try to take a view at the logs and see why it doesn't boot, but that is too much for my actual knowledge.

If anyone's got any idea, I'd be glad to read your thoughts.

Thanks in advance