I got a MotoRazr V3c phone second-hand recently. I found when I opened it up, the keyboard lit up instantly, but it was difficult to get the main display lit. I pressed the key indicated in the manual for lighting the display, but it always took a long time to light up. Then each time subsequently I wanted to get the display to light up, I had to remove and replace the battery. I was also asked for the Pin Number. More recently it became even more difficult to get the display lit. And now it will not light up at all. What could be wrong? Do I need a new battery? Or is it more serious?