2) LenovoVibe S1 Drivers & Mediatek USB VCOM Drivers – Drivers
3) Lenovo_Vibe_S1_TWRP-18.104.22.168-M_by_SevenMaxs.zip +
SuperSu TWRP-22.214.171.124-M_by_SevenMaxs.zip +
Enable USB Debugging on your device.
Go to > Settings > Developer Options > USB Debugging.
If Developer Options is not located under settings then enable it by going to Settings > About Phone > Device Info and tap on Build Number for about 7-8 times. And then go back and follow the previous step.
Step 1: Install the Lenovo Vibe S1 Driver & Mediatek Driver ( first go to smartphone driver and install "dpinst.exe" then install Usb VCOM driver. to do that please refer google to how to do it in your current OS
Step 2: Extract SP Flash Tools on your desktop
Step 3: Extract TWRP folder on your desktop
Step 4: Open flash_tool.exe from the SP Flash Tools folder and clock Scatter-loading and then browse the TWRP folder and select the MT6752_Android_scatter.txt
Step 5: In the Flash Tool Window Press CTRL + SHIFT + O a new options window will open. Click download and then tick USB Checksum and close the window
Step 6: Now click the download button
Step 7: Switch off your Lenovo Vibe S1 and then connect it using the USB to the computer/laptop
Step 8: You will get the Download Complete window within a moment
9) Remove the cable and press volume up and down + powerkey together and wait for the the lenovo logo or vibrate, it will go to twrp if you see black scree please wait for 2 mintues after twrp come copy the "UPDATE-SuperSU-v2.46" file to the phone and flash it
Note: Custom Recovery of SevenMaxs is the current updated recovery available but when you try to Wipe (dalvik,cache,system,data,etc) it will take more time ,you have to wait it to complete other than this no other issue
All the above are taken from different resources so if you find any difficulty ask to known experts.
Thanks to @techolite.com , @supersayan1000