Motorola V400

i have had my v400 for 2 weeks by now.i had used phone tool to upload some ringtones and wallpapers last night.everything seems goin fine.but today after i uploaded another 2 or 3 ringtones,it was ok for awhile,then like 2 hours later,when i was gonna use my phone,it went black.i try to press the power button,and it goes that the back light went on and off,then stay off for couple of seconds,then went back on and off again and again...just keep goin like this. should i hard reset the phone? if that so,how i do that? or should i do something else? is the phone dead? please help!!!