This system supports sixth-generation Skylake CPUs only - it will not run a 7th-generation Kaby Lake CPU.
Return the CPU for an i5-6500.
If the original CPU doesn't work after reinstallation, unplug the system, hold the power button for 30 sec. and then reconnect the power and try again. It should start up -- if it doesn't, and there's no sign of life at all, you may have fried the mainboard by installing the incompatible Kaby Lake CPU.