Regarding battery replacement, as an option to original, try MSM HK Power Series (Green Power Series)... almost same perfomance and cheap price ... Php 350 - 450...
@Altae: Remove your battery for few minutes (make it 5 or so). Insert batt back. Reflash using PC odin with some dr ketan stock GB. Once rooted, upgrade to ICS (for sure you know safe kernel for this, no factory reset here) then go back here to J...
For ICS rom, mostly the procedure for flashing:
1.) Flash Abyss Kernel
2.) 3 Wipes
3.) Install Rom
Also check the OP for more accurate procedure :)
Reflash it with PC odin (Again? :) )... refer to Dr Ketan... I encounter same issues before, I just try try to reflash old GB... link at #4