[How to] Flashing kernel

I have a rooted HTC one M9. I saw the HTCU tag so the device bootloader is also unlocked. Android version is 5.0.2

I compiled a custom kernel and updated it using abootimage.

I then tried:

Code:

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adb reboot bootloader
fastboot boot boot.img
adb wait-for-device shell

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I could use also

Code:

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fastboot flash boot boot.img

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but i want for the begining the boot.img to be lost on reboot.

The device is waiting in fastboot Menu with following options:
Reboot
Reboot to bootloader
Boot to download mode
Boot to recovery mode
Power down

When i give command:

Code:

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fastboot devices

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I get no device (empty list).

How can i update the kernel?
Is there a problem with fastboot?

Download from this link