Can't boot MacOSX from HDD or USB

I modified some kexts and changed the config.plist on my HDD clover EFI and I can't boot from it anymore. So I decided to try booting from the USB instead. I formatted to USB into MSDOS-FAT and then installed the latest clover on it with the boxes "Install for UEFI Only", "Install Clover in the ESP", and "OsxAptioFixDrv-64" checked. But when I go into the bootloader and try booting MacOSX, I get a black screen,