Sounds like the wii had bootmii boot2 (or was configured via priiloader to boot into bootmii for some reason, but unlikely under the circumstances).
It's pretty unlikely she could've uninstalled or updated your boot2. So again probably hardware.
Have u tried booting it without your sd card? In the unlikely scenario you have sneek files on your sd card and it's failing or slow to launch your emulated nand, it could lead to a blackscreen. But removing the sd card would ensure it tries to launch the real nand system menu (whereas on a bootmii boot2 wii it would automatically boot neek or bootmii if it detects their corresponding files on the SD card). I doubt this is the case, but thought it was worth mentioning, maybe it will help someone else reading this years from now.