samsang galaxy core gt-i8262 cant enter recovery mode

[prince raj kumar]

plizzz can any body help me........i hard reseted my samsang galaxy core gt-i8262......but afterwards when i try to enter recovery mode to install a custom rom......and i cant enter recovery mode........i tried pressing vol up+home+power button.......and the mobile long viberates & samsang logo appears but after that it viberates every 4-5 sec and after leaving the buttons the mobile boots normally