At clover boot menu hit the space bar once it will load a screen to select many boot arg. Options. Try selecting -v verbose mode, -x safe mode, etc... there are many options to try to get it booted. Start with verbose mode and see where it stops and try to take a picture of it.
Another thing to consider is the clover config.plist, when you load clover bootloader it has a MacBook 1.1 definition default and many settings for general use. If you already have a previous config.plist form previous build try replacing it.
In clover Kext folder place FakeSMCkext, and possibly NullCPUpowermanagementkext in the "other" folder.
Usually it's the FakeSMCkext missing in the "other"folder that kills the boot process.
To access the clover boot folder use EFIMounter it's free, this will open up the clover EFI folder where you need to make all these changes. If you have one disk on a working system and plug in just one USB (bootloader) then you should select disk1s1, for EFIMoumter target disk. The disk0s1 is the working Mac or hack drive EFI partition.
Hope this helps, start with the FakeSMCKext in other folder first, this is usually the Apple stop or freeze at start of boot process. It's too bad that Unibeast and clover do not automatically add that to the other folder it would make most of the posts for help unnneccessary or for other issues which are less common.
