Ok , two things may help. The OS on the BB is corrupt and unless the phone is defective you can try to replace the operating system. Itxxx8217;s not hard to do. I have included two links to assist in the replacement. READ both and follow the instructions. If you have desktop manager and made a backup, all your contacts and emails will be put back when your finished. If you do not have DM , you can go to RIM and get a free copy for the PC.
Replacing the OS is one option. the other is to borrow a battery and see if it works then. Generally the blinking led's indicate the OS is bad but trying the battery is easy if you can borrow one.
DM link BlackBerry - Support & Services
Blackberry information link KB04596-BlackBerry smartphone does not turn on and the LED flashes
Link from Blackberry FAQ site, Is your BlackBerry Nuked? - BlackBerryFAQ