Ps4 Pro Beeps, no light comes, and the system does not start-up

Hi everyone, I have owned my PS4 pro since 2017. Recently, I started noticing that the system was making a very loud noise, presumably from fan. Then, I decided to open up the console and replace the thermal paste. After doing all that, I put together the console, tried starting it up but to no avail. What could be the issue? I have checked many times the ribbon cables, the power supply cables and all…… Could it be the thermal pads coz I recall not noticing all the thermal pads on the memory modules when I last opened up the ps4. Thank you for the help……;)