UPDATE!!!

In order to fix this issue, you must disconnect battery, hold power button for 30 seconds, plug back in the battery, hold FN and power, and wait until the system shows its slight sign of life, with it being 2 red 4 red. After this you must close the lid, unplug the system from AC, and open the lid on battery. This has resurrected both my Alienware X15 R2s. their both specd with RTX3080TIs, i9 12900k, and a 240hz display. Hope this message finds anyone with the same issue as me and prevents months worth of work and research just like I had to do, along with hundreds in repair...

Bit late to this, but same story with 2 identical X15 R2s I own, the thing that surprises me is both systems had went when plugged through the type-c port. This lead me to the conclusion that it was a power delivery fault, and upon further research there is a video titled " [B]This Alienware Died… I Hot-Wired It Back to Life", [/B]Which shows the tech re-program a KB9542GF. The symptoms are the same and the only part-sign of life that i ever got was plugging the system in and holding the power button and FN for 30 seconds - which gave me a couple red flashes of the Alienware head....