That's what I did, it's called test point. The only thing I didn't tried was windows 10. I tried win7 32bit and win8 64bit in every single way possible with drivers installed.If nothing causes the phone to answer, entering the EDL mode is done by removing the back cover, removing the battery and connecting two dots on the motherboard.
There is a complete description of the procedure,
if i remember well in xda-developers.
I already did that. My phone is without the cover, battery disconnect and test point still no detectingMine too. No lights, no vibration, no screen, no sound, no charging, no doing. Are you going to try to follow what the guy said above? trying to remove the back cover?
I'm pretty sure I did the correct steps. Somehow something on motherboard should have been locked, something like preloader or the storage...If it didn't work, you didn't respect the succession of the operation very well.
Follow the sequence of the operation very closely and see if your intervention was identical.