Install Magisk / root your phone
You need to extract your boot.img first (see other page)
- install magisk app (make tripple sure to pick the right one ... bad people out there ...)
- copy boot.img on your device
- open app, hit install
- selekt your boot.img
- you wont finde the patched img on your PC due to RW permissions, i suggest you to share the file via DataExplorer via an messenger/encrypted e-mail)
- reboot to bootloader
- flash patched boot img
fastboot flash boot PATCHED_BOOT.IMG
- reboot
- Open magist app
- done