My problem solve
Tanks from "riobenny" user for this help:
remove ur battery.
then, u must turn on ur phone by pressing power button, and volume down. hold those two button, till u find android puppet logo, and a triangle.
if previously u run eclair ---> touch the bottom screen, choose wipe data/ factory reset, and choose wipe cache. (navigation entirely using touch screen)
if previously u run froyo ---> press vol up and vol down together, choose wipe data/ factory reset, and choose wipe cache (the navigation is using vol key, to choose using power button)
after u wipe all data and cache, press REBOOT system.
but.... IMMEDIATELY after u press REBOOT, u must press vol up buttong and HOLD for around 6 seconds and then release.
after that, ur screen will show boatloader mode, and u can flash it again using FULL SBF froyo for fresh one.