I'm sorry but I'm quite experienced in using Spreadtrum's ResearchDownload software. I tried to use your uploaded backup, but some files have to be truncated by a hex editor before flashing or the flashing process will stop due size error. The system.img is still not working. I'm not just talking but I've tried to flash your files and they don't work.
Btw, here is the latest Spreadtrum flasher:
ResearchDownload_R2.9.7001
Here are some working .pac files:
Feiting_A7100_6820_2.3.5_c910_hteng_s5_en_4.0_v01 Feiting_N9300_C909_HT_EN_V04_20121017 Feiting_N9300_C909_JF_EN_v03-235_20121120 S5830i_20121006_c909_JF_EAHC_V12 S5830i_20121120_c909_JF_EN_v03-235