Revive a dead phone?
It could be that the phone is stuck in a boot loop at or before the OS has a chance to load. According to XDA, to get into the recovery partition, start with this: Home button + Volume button - + On button.

If you can get into fastboot mode, you can issue a command from the PC with a usb cable. After seeing if the device is there with "fastboot devices", try "fastboot erase cache" and try to boot. If that fails, "fastboot -w" will essentially do a factory data reset. Of course, your coworker will lose all her data, but at least the phone might boot.