Install unsigned boot.img

[AnotherElk]

Here’s how to sign TWRP images for booting them via fastboot without flashing them.
I don’t know whether it would be the same for your boot.img, but you could have a try …

Linux/ macOS

TWRP 3.1.1-1 boot issue

For reference: I have a guide on my blog which should work on Linux/macOS: https://z3ntu.github.io/2017/06/16/Signing-boot-images.html

Windows

TWRP 3.1.1-1 boot issue

I looked into this on Windows and got me a signed current TWRP image that fastboot boots on my phone (yes, I’m surprised myself). Here goes … and you don’t have to bother with the whole key stuff, we’ll just download some … Install Java (if not already installed). Make (or look for) a directory to put stuff into. Download BootSignature.jar from @z3ntu’s place to the directory (URL found here). Download SignApk.zip (found here), from SignApk.zip extract the two files testkey.pk8 and tes…