I had the same problem with my Lenovo Vibe P1.
What I did was I pressed down the volume keys + power button and as soon as the screen lights up, leave the power button but still hold the volume keys down. It would enter another screen whereby you'd see options like "reboot, install update package, wipe user data" and "power off". Instead of going for a factory reset, I selected "install update package" and just clicked on the yes option that follows on the next screen(it reads something like install from internal memory).
The update of course failed because I didn't have an update.zip package in my phone. Once that is done, go back to the menu and select power off. Switch it back on after a few seconds and see if that works for you

...