OnePlus 6T Did "fastboot boot" just delete all my encrypted data? Today after a successful(Booted, worked fine all day) OTA manual upgrade(downloaded latest zip and flashed) I decided to reinstall TWRP in order to reroot. However, after running first "fastboot flash recovery twrp.img" then "fastboot boot twrp.img", I am no longer prompted to enter my passcode(which I know) to decrypt the device, and the /system partition is empty in the TWRP file manager. The sdcard partition is filled with my encrypted files(assuming by their base64 names). 
I dont think any of my actions in TWRP were significant, except possibly when I flashed the twrp.img to have the recovery be persistent. (When I launched TWRP for the first time, I wasn't prompted for my password to decrypt then either, so I assume the damage was already done)
I have tried "twrp decrypt [password]" in the twrp terminal but I get "Failed to decrypt data".
When I try boot into system, I either bootloop or TWRP launches instead.

A. Is there a way to reflash my system(e.g Can I just flash the same update.zip) and be back to normal
Or B. Can I retrieve and decrypt my data, given that I know my lockscreen passcode which is normally used to decrypt it.

Here is everything I wrote in my command prompt

Here is ls -la /
Full credit to alecxs for this answer. Posting incase anybody else has the same problem in the future.


Download stock image(Mine was oneplus.com/uk/support/softwareupgrade/details?code=9)
Use extract_android_ota_payload-master to split the payload.bin inside the zip
(Method for step 2 https://pastebin.com/RfEHuvu7 , I did this on linux because my linux machine has python2 installed, no other reason)
Flash the boot.img and boot with twrp
(Step 3 https://pastebin.com/Gp9aJq36)