Hi guys,
A good lesson learned after rewriting PRELOADER and DSP_BL with another phone's.
The phone was dead, no led when connected to usb and of course no activity on flash tool as the usb port was not activating.
Basically as i understand the critical blocks are the first 5, PRELOADER and DSP_BL (that's why flash tool has them with red text) and also MBR, EBR1 and UBOOT.
Anyway after having the phone in this condition i was searching for unbricking methods and i found this good thread in the Russian site forum.china-iphone.ru/viewtopic.php?p=730752
I understood the principle although the translation was not good, i searched with the multimeter for points that with connected the usb cable will have a voltage near the battery voltage as was suggested at that post. Finaly i found the two points that are shown in the second picture (points 1 and 2).
Without battery, connected the usb cable to the pc and opened the device manager.
I turned the multimeter to the location that acts like jumper, using the multimeter cables was very handy for that.
I touched it some times, nothing was happening and decided to keep it alittle more, the list moved in device manager but nothing special.
So i decided to keep it more than 5 seconds, the device manager recognized Mediatek USB port, that was. The drivers were there installed from previous attempts. I also had installed manually as legacy devices some extra from the mediatek driver list.
I started flash tool, loaded the scatter file of the ROM i use for this phone and selected only the first 5 blocks and pressed download.
I connected the two points and kept them like that till flashing finished.
I placed the battery and pushed it to touch the pins (cause without the back frame don't fits ok) and the red led was working now.
Assembled it back, loaded again the flash tool but now with all the blocks selected and did the flashing now using the usual way with the battery.
That's it after flashing finished the phone booted ok and started the setup.
I had a complete backup that i did with the MTKdroidTools and got back the phone as it was exactly before flashing the wrong rom.
For anyone that has the phone in same bad condition and wants to try this method of course as usual i must say is done AT YOUR OWN RISK
If there is a possibility to have the phone replaced do it.