Try replace cmos battery with a new battery and clear cmos settings via motherboard CLR CMOS jumper pins.

on 7040 mt there is a set of JMP1 jumper pins 1-6. Pin5-6 short are for clear cmos. Instructions are print out on board.

@redxps630 Thanks for reply......

I already have replaced CMOS battey..

and couldnt find Jumper pins 1-6..   can see one Jumper connected in PWCLR ..

should I try power on after removing it ??

That is clear password jumper.  However, you can use that jumper to connect the clear cmos pins.  It located at the edge of motherboard by the power supply and about at the middle of the PCIe x16 slot.

Leave it on the clear cmos about 5 seconds then remove it.  Put the jumper back onto password pins.

No, that is the USB connector (CLINK).  Look more to your left, around the middle of a long blue slot.

@redxps630 , I think OP has an SFF unit, not a tower.

@redxps630  @Chino de Oro 

 Thans for reply

Seems like one PIN is gone frm my board < Hope this is the PINs you are asking to use jumper..

I Found it.. CMCLR pins..

Tried to power ON after putting Jumper on it for 5 seconds..

Now i can see Mouse LED is glowing for some times , but nothing on display..

Tried both DP and HDMI...

I was trying to prevent you from shorting the wrong jumpers and may cause electrical damage to your board.  I did not mean to interrupt your troubleshooting with Red.  You were in capable good hand.

While waiting for Red, you can try some more troubleshooting yourself.  Assuming that you have good working monitor and cable, you can try removing all PCIe cards and all memory stick.  Unplug all drives.  Power on your machine with just your CPU to trigger diagnostics light, error codes and maybe video.

If you get some good result (display), start to put back one component at a time until your machine breaks again.  That will tell you the cause.

If you get nothing change, test your power supply.

Thanks chino for helping OP.  agree w diagnostic steps in no post situation.

I may add, it is helpful to note color of power button led. If amber (steady or blinking), it would suggest either motherboard or psu issue.  If led is steady white, that is a good sign.  re: LED light on CPU glows White, does this mean power button led?

chino is also correct noting it is 7040 SFF.

It seems standard config is have hdmi DP on board video but no VGA (optional)

did you manage to solve it? I am going through the same situation with a sff. no video