I need some help. I unlocked, rooted and flashed a ROM to her Nexus. She didn't like it, so I flashed a different ROM. She didn't like that one either, so she wanted to go back to stock. I used a toolkit to flash her phone back to stock, then I unlocked and rooted it again. The phone worked for a while but this afternoon, it rebooted. Now it won't get past the boot animation. She said it was like that for about an hour. Any ideas on how I can get it to work again?