Ps4 slow and crashes

I recently bought a second hand original Ps4 it turns on and starts up fine but it freezes after a little wile in the menu and won’t load up any games there’s only one game installed and it’s nothing over the top you go into it and it just stays loading on the game then eventually the screen will go black you can barely hear the fan so I removed the top cover of the ps4 and the fan is spinning it does feel hot quick tho is it worth replacing the fan thermal paste and hard drive or am I wasteing time and money

Remove HardDrive and connect to PC and use software like crystal Diskinfo see if it’s been aged or having error.
I recently got a OG PS4 came in with an original HGST HDD inside been running 8k+ hours and it also boots to system fine but most time freeze screen after 5min, cant even turn to sleep but only force shutdown.

If it turns and goes into the menu, i would say the ps4 is fine, should clean of dust and check the hard drive via pc by either crystal disk or by merely using command prompt. CMD (command prompt) can check for errors and bad sectors. However changing out the hdd if faulty is very simple procedure. Next check dust on the fan and heat sink. As long as it boots up and you are in the menu means motherboard, apu are fine.