I have rooted Lenovo Vibe K5 and I had installed CM 13 (Marshmallow). It was working well, but because of some need, I had to install CM 12.1 (Lollipop) and I tried installing through TWRP recovery CM 12.1. I wiped Dalvik, Cache, and System and installed CM 12.1 successfully and was asked to reboot the system and I clicked on reboot. After that, it didn't turn on, not even in recovery mode by pressing and holding the Volume + and Power buttons.
Then I tried to flash it again with PC but it's not showing in CMD as well. It shows the error "Device not found" in CMD and in Windows notification, it shows "USB Device not recognized".