[essayn]

Any advice how to flash it ?

ADB or better: via Fastboot.

While in fastboot type fastboot devices in the command prompt, to check if your device will be recognized.

Then just type, one by one, & "enter" after each step:

fastboot erase recovery
fastboot flash recovery recovery.img
fastboot reboot

or, if you just want to boot once into the c-recovery:


fastboot boot recovery.img
fastboot reboot


Besides that, the web is full of tutorials and several commandos. You may read this, e.a.