As with some other Lenovo devices, the firmware for Lenovo Vibe K5 A6020i36 can only be flashed via QPST.
Download from below and follow instructions at post end to learn how to flash, and or download QPST Tool.
Downloads:
File Name: Lenovo_Vibe_K5_A6020l36.rar
Size: 1 GB
Android Version: 5.1 (Lollipop)
Firmware Link – Download or Download
!Password: www.stockrom.net
Read: Download Lenovo Vibe K5 A6020a40 official firmware
Flashing Instructions:
Click here to download QPST and learn how to use the tool.