Nexus 6P stuck on bootloop after rooting So today I bought a used Nexus 6P for the purpose of installing Kali Nethunter on it, and then after some searching I found out that I should root the device first.

So I followed this guide using SuperSU, I installed the SuperSU from this website, the phone then hung on the Google logo for like 30 minutes, then I found out that the SuperSU project is dead.

I said ok maybe because it's an older phone the root should work and then I entered recovery mode through TWRP and went to the terminal and I saw the # sign and to maker sure I ran the command whoami and it gave me root, and then I read that if I'm stuck in a bootloop I should reflash the ROM that I already have installed, but I said it wouldn't make a difference if I flashed Nethunter, it's a new ROM anyway, and now it's been stuck on the Google logo for another 30 minutes.
I found a solution to this which is flashing the stock ROM using the adb/fastboot tools, but I used an older version because the latest one didn't work for some reason and I followed the guide on google's website hope that'll help someone. :)