Enable bootloader screen for Lenovo Vibe Z

I pressed and held volume up key for sometime and my Lenovo Vibe Z is seems to be bricked (not charging or switching on). I would like to get into to the boot-loader screen to factory reset the device.
Two things:

1. Please help me with the key combinations required to get into boot-loader.
2. Or ways to unlock the boot-loader in Lenovo Vibe Z.