I need help identifying why prebuilt fails to start

It was working fine until I decided to put it apart 🙄
The plan was to transfer its contents to a larger case. But the Mb and the CPU wouldn't fit.
Now that I had put it back together something is not the way it used to be.
I have tried various things, including replacing the CPU, but still fails to start, and I'm out of ideas.
When I press the start button the pc starts, I can hear the HD spinning, and the PSU fan working, but nothing shows on the monitor. That's why I tried another GPU. I had made sure the GPU is well plugged every time.
The only thing that's different now is that I am not plugging back the DVD drive. I hope this is not the reason because I don't need it, and it's a real pain to cram it in such a tight space.

Specs: Acer Nitro 50 N50-600-EB14 2019,

Did you plug the 4-pin CPU power connector from the PSU back into the motherboard?

NavyLCDR said:

Did you plug the 4-pin CPU power connector from the PSU back into the motherboard?

Damn! For a moment I thought you had found it - I had second thoughts. But it is plugged
Anything else?

Just for the heck of it, connect the DVD and see what happens. Also recheck all the cables and connections, specially the ones that go into the PSU (if you have a modular one).

Are the RAM modules properly seated? Have you tried resetting the BIOS?

Does the monitor light show orange or green or neither?
If neither,then it probably indicates a faulty power supply or Graphics card connection.
Is it possible to try the monitor on a different pc,using your leads?

I was just trying to unplug the monitor cable and one of the screws (not sure where from) came alone:
Pasteall.org
Maybe this is the reason... (I hope).
Nope, it wasn't I shot some photos, I know it's not the same to being here, but one never knows...

1. Pasteall.org
In this one you can see the black SATA cable plugged to the SATA 1 port. I think that's where it was originally (I can't recall). But I am sure it is the SATA 1 port.
2. Pasteall.org
3. Pasteall.org
This metal board/panel where the drives seat is upside down in the photo, and the HD is unplugged for the photo.
4. Pasteall.org

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eddman said:

Just for the heck of it, connect the DVD and see what happens.

I just did, nothing changed though

eddman said:

Also recheck all the cables and connections, specially the ones that go into the PSU (if you have a modular one).

It's not modular. But yeah, I have checked them and rechecked them.

eddman said:

Are the RAM modules properly seated?

I didn't have to remove the ram at all. Neither the CPU. I removed the MoBo with both, attempted to make it fit in the new case, and that was it. However I still have checked it, but it looks ok.

eddman said:

Have you tried resetting the BIOS?

I only know how to do it with the monitor. Is there supposed to be a manual way directly in the BIOS chip on the MoBo?

I have been plugging the HD to SATA 1, and the DVD to SATA 2. I hope this is the way it was.
There's only 3 SATA ports. I used use the 3rd one for a SSD. I have not plug it back to keep things simple. This SSD didn't come with the pc originally. I believe that's where I have Linux installed.

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joeandmarg0 said:

Does the monitor light show orange or green or neither?
If neither,then it probably indicates a faulty power supply or Graphics card connection.
Is it possible to try the monitor on a different pc,using your leads?

Yes, the light shows orange.
Also, I plugged it to my laptop with an HDMI cable and it worked.
Just in case the problem was the DVI cable, I replaced it with the HDMI cable, to no avail, again.

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In case I didn't mention it...
The MoBo, CPU, PSU, and HD do start, from what I can tell. Except nothing shows in the monitor.
10 to 15 seconds after it reboots, and does it again.
I just tried swapping the SATA drives (DVD to SATA 1 and the HD to SATA 2), to no avail either.


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Have you tried unplugging the power cord from the wall or PSU, remove the motherboard CMOS battery. Press and hold the power button for a few seconds.

A local technician says that the motherboard is probably "shocked". That I shouldn't plug it to the PSU anymore and take an appointment with them.
Any thoughts?

Sounds like he will make a bit of money from you with things like "shocked", lol