PC Dead. Power button does nothing.

[AverageHardware]

I'm running into an issue where one of the PCs I have will not turn on. When the power button is pressed, nothing happens. No fans, no HDDs, no display output. Dead. There is an indicator light on the motherboard that IS illuminated. This is the second time this has been a problem, and it is stumping me.

 

1st time:

I suspected that the PSU was toast, because that was just common sense, right? Well, I tested the computer with an old PSU I had laying around, and it booted just fine. Everything functioned properly. I ordered a new PSU, slapped it in, and it DIDNT work. Same thing. Completely dead when the power button was pressed(Yes, I did bridge the pins to confirm it wasn't the switch. Same result). This really stumped me. Why did a new working PSU not work, but an old OEM unit work just fine? After tinkering with it, I took the CMOS battery out for 30 secs, popped it back in, and it worked just fine with the NEW PSU. Strange. So I was curious as to whether the original PSU was actually bad or not, and after removing the CMOS for 30 seconds again, it booted just fine. I ended up using the new PSU anyways because it's well..new. Slapped an OLD(probably 8~ years) battery in there, and it worked just fine. For a few months.

 

This time:

Same symptoms. Completely dead. Was running fine, but it was shutdown for about a week, and now nothing happens.

 

What could be causing this issue? Can a simple CMOS battery really keep a system completely dead? Would a new CMOS battery solve all my problems? Or is something more serious?

 

Any help is appreciated. Will answer any questions asked.

 

Hardware if it matters:

i5 2320

8GB ram

2x 1TB HDDs

430watt PSU

GT 630

[Zenedge]

yeah, a cmos battery can stop a pc from turning on. idk how or why, but it just is.

but they're easy to replace 

[AverageHardware]

yeah, a cmos battery can stop a pc from turning on. idk how or why, but it just is.

but they're easy to replace 

Yeah, just seemed strange. Usually it just resets the BIOS, but I've never heard of it keeping a PC dead. Thanks for the post good sir.