Question PC shows no sign of power, Motherboard problem.

Mar 18, 2020
PC components:
CPU - Ryzen 5 2600
MOBO -Asus Strix B450-f
GPU - Gygabite RX 5700 XT
RAM - Trident Z 16 GB
PSU - Coolermaster masterwatt 650 Watt 80+ bronze

So about a month ago I bought a brand new RX 5700 XT to uprade from my 1060 that struggled running 3440x1440 for most intense games. after recieving the graphics card I installed it, downloaded drivers, got rid of the old ones, did everything that need to be done. I tested it by playing a few minutes of Red Dead Redemption 2, about 10 minutes later I shut down my pc and had to leave the house. The next morning I came back to play some games but my PC was showing no signs of power at all, the powersupply was on, but nothing happened when I pressed the start button. So I starting testing, firstly taking the graphics card out and resetting the CMOS but nothing happened, tried again, still nothing happened. The next day I came back to it to try fix it again since i had time and after switch the powersupply off i started taking the PC apart, first i took the wifi card out and thought i should drain the power from the pc by holding the power button for a couple seconds, and supprisingly the PC light up and turned on with the little bit of power. So I turned on the powersupply and put the component back in and my PC worked perfectly again for a couple of hours. That night i turned the PC off went to be and the next day I came back it showed no power again! So I pulled it apart again, reset the CMOS as I did before and for about 4 days of personal testing the pc still had no power, I also tried . I managed to get a spare motherboard of my friend so I was able to test my other components. Once i rebuilt the PC with the new motherboard it work perfectly, I did some stress testing and benchmarks, everything was performing as usual, and the new graphics card was great. I sent my motherboard off the Asus and while I waited to get it back I used my friends motherboard which for the month I had it, i had absolutely no problems, except my fan wouldn't light up due to not having the correct rgb header but oh well. Anyway I have only just recieved my motherboard back from Asus and after rebuilding the Pc it worked again, (p.s asus did somewhat fix the motherboard as it had 4 dead sata ports but 2 still worked). So the next day I go to turn it on and of course there is no signs of power, once again i checked the powersupply, cpu, gpu, everything and made sure they were working. So from my personal conclusion, something is definitely wrong with the motherboard, dont know what though, and I want to know whether to try get a refund and by a completely new motherboard, get a replacement or try get Asus to fix it again. If you have any idea whats wrong with it please let me know!