Pc not start

[Kapil77]

The CPU is not turning on. I have a MSI Z490-A pro motherboard and the processor is Intel i3. The CPU light in the CPU is turning on and off.

[AlHill]

Which i3 processor?  There is no "light" in the cpu.

AC plugged in?

Have you checked your power supply?  Is the 4-pin power connectoir plugged in?

Doc (not an Intel employee or contractor)
[If you find any Intel driver you might need, download and save it now.]

[VARADHARAJAN]

Remove CMOS battery , and replace with a New CMOS  

Check that your processor is compatible with the motherboard.

The processor is seated properly in the slot.

Did you install the Cooler properly? 

Did you apply thermal paste properly did you ATX cable, CPU cable, and fan cable in MB?

Check do you installed a validated power supply unit by MB.

Also, check the Same model same frequency  RAM module in MB, those RAMs are approved by MB.

Check if any metal pieces are residing on the motherboard.

Check all the cables are tightened properly and make sure all connections are good, not loose connections.

Check SMPS fan is running.