Here's the thing. I want to go back to the stock ROM but I didn't do a nandroid backup. Stupid of me, I know. Anyway, I got from a friend the stock recovery.img(184.108.40.206) and also the stock ROM (U8800V100R001C00B135SP02(WIND-HELLAS)). It is a greek ROM. I applied the recovery.img and now I'm downgraded to 220.127.116.11 from 18.104.22.168. Then, I booted in clockworkmod and tried to apply the stock ROM's .zip . However, I get "Installation aborted" message all the time. I cannot understand where I'm wrong. Maybe someone that did return to stock ROM can help me out here.
edit: Sanpsa, you said that someone should follow the instructions of the extracted files. You mean "UPDATE.APP" and "UPDATE_CUST.APP" files? In my stock ROM with these files you can upgrade the ROM. Is it necessary to upgrade the ROM and then apply the .zip? I don't get it...