Most of this still applies:

https://www.dell.com/community/Alienware-General-Read-Only/Alienware-Desktop-General-Hardware-Troubleshooting/m-p/5555517#M57436

But unless you have a spare (known good) power-supply and/or a Digital PC Power-Supply Tester, probably better to take it to a computer shop.

They will also be setup to replace the motherboard if necessary. Thing is, only a genuine Aurora-R7 motherboard will run the LED-lights and/or top-panel ports.

Also, unless you know the serial-key burned-into your BIOS, you might have to buy a new copy of Windows-10.

Come to think of it, I think Dell might have some "out of warranty" repair services available. If interested in that, give Alienware Tech Support a call.

Thanks for the reply @Tesla1856. I checked and Dell offers a renewal for Onsite/In-Home Service After Remote Diagnosis at $99 and a $49 reinstatement fee. Will contact them to see what that really gets me. I might pick up a PSU tester. I have a multimeter but it looks at lot easier to just invest in the tester and if it's a bad PSU, order a new one. From my reading you have to be careful to get the right PSU to support the GPU power cable on the mobo. I have some old Dell's I need to check to see if I could pull a PSU for testing. Not hopeful about that. If it is the motherboard definitely will deal with Dell at that point.

1. Will contact them to see what that really gets me.

2. I might pick up a PSU tester.

3. I have a multimeter but it looks at lot easier to just invest in the tester and if it's a bad PSU, order a new one.

4. From my reading you have to be careful to get the right PSU to support the GPU power cable on the mobo. I have some old Dell's I need to check to see if I could pull a PSU for testing. Not hopeful about that.

5. If it is the motherboard definitely will deal with Dell at that point.

===================

1. Cool

2. Like this one. Also tests for PG (Power-Good). Good to have in toolbox in general.

3. Right. 

4. A Delta-made Dell 850w will work. It has plenty of EPS-style outputs/connectors (for CPU and GPU-Power).

With after-market modular, be sure to swap all cables also. The various Modular cables are matched to each specific model of PS.  

5. And then you keep replacing things until it works. 

Get a good UPS (like APC-1350 with AVR/LCD).

R7 still has integrated DP video port on motherboard even when it is covered by plastic tab (#4 in back panel). Pull any old working Dell psu with 24/4 pin and you can test the R7 board without discrete gpu.  R7 psu passing bist is not guarantee it is not failing.

1. R7 psu passing bist is not guarantee it is not failing.

2. R7 still has integrated DP video port on motherboard even when it is covered by plastic tab (#4 in back panel). Pull any old working Dell psu with 24/4 pin and you can test the R7 board without discrete gpu. 

==================

1. Correct

2. Yeah, always forget which have it. Good call-out. But as should be documented in the linked-TS-thread ... making system as basic as possible includes pulling discrete video-card and using on-board video if available.

You can also have issues with power-switch or whole front-panel if "soft power-switch" integrated into solid-state panel/circuit. Can even make "jump starting" challenging.

Thanks for the tip @redxps630. I tried this with an old known working PSU and the DP port and still won't get anything when pushing the power button on the front top panel.

Re: I tried this with an old known working PSU and the DP port and still won't get anything when pushing the power button on the front top panel.

in that case it is not a bad psu that caused no power.

try clear cmos settings.

1. Locate the CMOS jumper (P217) on the system board. For information on the location of the CMOS jumper, see " System-board components".
2. Disconnect the system-board power cable from the system board.
3. Remove the jumper plug from pins 217 and replace it on pins 216 (P216).
4. Wait for 5 seconds.
5. Remove the jumper plug from pins 216 and replace it on pins 217.
6. Connect the system-board power cable to the system board.
    
   

   The other thing to test is jump start the power switch embedded in Dell proprietary 12 pin LED cable.

   Front panel power on the white 12 pin connector is:     PWR BTN +5V / Gnd

   R7:  1 2 3 4  5 6 7 8 9 10 11 12

   disconnect the LED controller cable connector (carefully and gently, do not pull on skinny wires), use a flat blade screw driver to short pin 3-4 momentarily.  This is effectively the same as pressing power button.  In case there is a circuit break somewhere between power button and the switching on of Pin 3-4, doing this test will bypass the break.
   
    
    

   

   
   

Thanks again @Tesla1856 for the information. Tried an old working 375W PSU with same results, nothing happens when I press the power button on the top front of the case. I just had the 24 pin and CPU hooked up and monitor on the DP motherboard port and USB wired mouse and keyboard.

Ok, will give that a try. Thanks!