Hello (hope it is not too late)
After 3 days of trial I finally managed to flash my lenovo p780 (4GB) that was in this condition. More or less I did what is described in most forums, the differences between the successful attempt and the previous ones were the following.
1. I used SPflash tools v5 (the latest I found)
2. I used a ROM version (I think) close to the original one .My phone had a number 140421 at the lower part of the battery, I downloaded P780_ROW_S226_140919_Rooted_SPFlash_TWRP
3. I connected the phone which was turned off,after pressing 'download'. After connecting it I did not press any buttons, just waited for about 30 sec
4. Compared to the video, I had chosen the Options/Download/DL DA all with checksum.
5. Before flashing I assosiated the .bin files of the downloaded ROM with the flash tools (right click on file, properties, opens with etc)
6. The whole process was done OFFLINE
I hope this helps, good luck.