Lenovo s860 Bricked, Recovery Crashes, No OS
I managed to repair it.

1) I installed the following android verion http://www.needrom.com/download/lenovo-s860/, but it upgrades to a chinese Vibe 2.0, which is very customised and has no Google Play Store, as weall as all other Google apps.

2) So I used the "Upgrade Firmware" option on the PC program (SP Flash Tool) instead of the "Download" one to install http://www.needrom.com/download/rom-stock-4-4/ (this site contains very precise instructions, check it out before doing any of the steps)

3) Now phone works perfectly, but it has IMEI connection problems - IMEI Invalid - Lenovo S860, rooted android 4.4.2, nothing works

4) KingoROOT seems to fix the IMEI problem

5) Phone up and running perfectly