(See also Downgrading from Lion to Snow Leopard on the latest Mac hardware)
Install Snow Leopard via a 10.6.7 universal installer disc (a MacBook Pro or iMac 10.6.7 "Mac OS X Install DVD" can be made universal via Joel Bruner's bash script 💾).
Install all updates*
From a Lion install, copy
/System/Library/Extensions/: AppleIntelHDGraphics.kext AppleIntelSNBGraphicsFB.kext
and
/System/Library/Extensions/IOPlatformPluginFamily.kext/Contents/Plugins/ACPI_SMC_PlatformPlugin.kext/Contents/Resources/: Macmini5_1.plist Macmini5_2.plist Macmini5_3.plist
into the same locations on the Mac Mini.
Run this script as root and reboot:
cd /System/Library/Extensions/IOPlatformPluginFamily.kext/Contents/PlugIns/ACPI_SMC_PlatformPlugin.kext/Contents/Resources
chown root:wheel Macmini5*
chmod 644 Macmini5*
cd /System/Library/Extensions
chown -R root:wheel AppleIntelHDGraphics.kext
chown -R root:wheel AppleIntelSNBGraphicsFB.kext
chmod -R 755 AppleIntelHDGraphics.kext
chmod -R 755 AppleIntelSNBGraphicsFB.kext
kextcache -system-prelinked-kernel
kextcache -system-caches
exit
echo 'Finished'
* Deuced civil of Apple to keep the old servers humming along:
/mac | Sep 07, 2020