What about DFU mode? Plug your phone into your computer (with iTunes running). Power off your phone, or in your case wait for it to restart.
Hold down both the lock button and home button for 10 seconds. Release the lock button but keep the home button pressed for 10 more seconds. iTunes should recognize your device, but the screen should be black.
There's no way your phone can restart completely in 3 seconds. Plug your phone into your computer and enable iTunes, wait for the screen to go black (this is the same as powering off if it's crashing/ restarting). Then follow the directions to enter DFU mode.
As the screen goes black your phone is rebooting from the crash, THAT is when you enter DFU mode by holding down the buttons (as I wrote above). You MUST plug your phone in with iTunes running.
Yes i have jailbreak before . Maybe i wont call it restart . U know when u have SBsettings on , then something u do , it crashes your springboard ? it will be on safe-mode . Usually you are able to restart the springboard on your own , but somehow mine automatically restarts . It's kinda like a loop , it crashes first , then it goes to safe-mode , then it restarts back to the usual and it crashes again .
So turining off is not possible . Even when i plug into itunes , my phone will keep vibrating as it keeps disconnect from itunes .
Oh, so it's like a respring? You should still be able to access the file system while your device is respringing. Have you ever used a program to access your files, like iFunBox?
Wait, I think I get what you're saying.
When your phone disconnects from iTunes, that means that it's rebooting. So wait for it to disconnect, THEN follow the steps to go into DFU mode. You'll have to be quick about it.