Welcome to the forum.
How old is your 600 watt psu from an old build?
Psu brand name?
Psu model name/number?
A failing power supply might be the cause of your boot problem.
Can you borrow a good quality psu to test with?
Do you have another brand new CMOS battery that you can try?
Have you tried putting your system to Sleep or Hibernation to see if you can wake your system without problems?
I changed your thread title to Extreme6.