In this case, as you said, I think the failure of power supply and motherboard is more likely. First, check whether the power supply can be started normally, and then see whether the output voltage of the power supply is correct. Then take out the memory stick and wipe it to see if it is good. If it's not good, remove the memory stick and turn it on to see if the motherboard can call the police. If it doesn't call the police, the probability is that the motherboard is broken. Get a new motherboard.