Blackjack 1 Locked...can't put in password

Well today I was messing with one of my friends phones(first generation Blackjack). Well i was kiddin around and put a pass word on her phone. I pressed thebutton at the top, scrolled to "Device Lock" and put in a four digit number. well after that it i turned it off. Well she goes to turn it back on and it didnt work. well we take the battery out and put it back in. it will bring the startup screen up then it brings to home page with a little tab at the bottom left saying "Unlock" well this is what it did the last time i did this, which was no big deal. but when you go to press the button the screen blacks out, until you click the scrolling wheel again. i dont know what to do, the battery was fully charged, the phone worked just fine before. she cant take it back to at@t b/c it had water damage w while back. but thats not the problem. the only thing I can think of is to just get her to reset it. but i have no idea how to do this. please any information would be greatly appreciated 😛

                                                                                                                                              -austen