1. First, u must install USB drivers for lenovo phab plus and activated USB Debugging mode
2. Copy Lenovo_PB1-770M_TWRP-22.214.171.124_by_SevenMaxs.zip into internal SD
3. Install Temporary TWRP Recovery :
Connect You Device to PC >> Extract TWRP-126.96.36.199_PB1-770M.7z >> Open the .bat file and wait the processes until you entered TWRP.
If you can't read the .bat text instruction, here is the translation :
echo 1. Press and hold the volume up button on the unit
echo 2. Press the Enter key on the keyboard of your PC
echo 3. after the appearance logitipa TWRP release the volume
4. After entered TWRP flash Lenovo_PB1-770M_TWRP-188.8.131.52_by_SevenMaxs.zip
5. Install superSU.zip u can search in XDA forum thread and your PHAB PLUS rooted permanently..
Credits to : sevenmaxs from lenovo russian forums
Do this at your own risk, dont forget to backup your system before doing this...