robing

GOT IT !!!!!  

I tried running "S1 Tool" as administrator (right click...  execute as admin....)  and it worked !!!!!   If it can be useful for others, here's the story...

Sony Xperia SP 5306 was doing weird things (calling the same person on and on, by itself!)  and other crazy behaviors....

Also, battery began to be very weak.... (hard to charge, lose its power very quickly...)

Tried software update using PC companion; (maybe because of battery but it WAS charged almost 100%....) phone crashed during update.   Hard bricked; nothing, no vibration....

Got a new battery, installed it (a pity...) and tried your method (test point) it WORKED with my 5306 using ZEUS deivers (changed drivers by right click on device in device manager)

To top it all, I was unable to flash firmware and here's the clue; Xperia SP needs version 0.9.18.6 of Androxyde Flashtool, otherwise it won't flash system.sin. 

Thanks a lot for this method well explained !!!!!!   My phone lives again !