XPS 9550 black screen/no POST or boot after pressing F8

I was trying to get into Safe Mode in Windows 10, and since I had not done so in a while I tried using the F8 key on boot. Instead of going to the Windows recovery screen (which I realize now is not accessed with F8), the Dell logo appeared with a blue progress bar underneath, but no text was present. After a couple seconds, the computer shut off. Since then, the screen backlight does not turn on and there is no display output, even from HDMI.

Here is what I have done so far to troubleshoot:

• Disconnected battery/unplugged AC adapter, then powered on
• Unplugged CMOS battery, powered on/off, plugged CMOS battery back in
• Tried fn+power
• Tried D+power (this did turn on the backlight and flash colors, but only this)
• Held down power button for 30 seconds to turn on and off
• Tried the BIOS recovery method (ctrl+esc with BIOS USB disk inserted)
• Unplugged NVMe SSD and powered on
• Powered on, then tapped F2 or F12 repeatedly to trigger BIOS configuration screen
• and multiple combinations of the above

My BIOS has also been upgraded to the latest version as of a couple weeks ago. In all cases except D+power, the screen did not turn on, nor did the keyboard backlight (including caps lock). While powered on, if I pressed the power button, the fans would spin up for a few seconds and then shut down.

I called Dell support who had me try a few of the troubleshooting methods above, which again did not work. He came to the conclusion that the motherboard was dead (a "mechanical failure") and said that it needed to be replaced. Since my laptop is not under warranty any longer, he said I would have to pay for the replacement part, which is currently not in stock.

While searching, I came across multiple other threads on this forum where people experienced the identical issue (no POST or screen output after pressing F8 on boot). Some were able to get their boards replaced as their laptops were under warranty. 

en.community.dell.com/support-forums/laptop/f/3518/t/19994479

en.community.dell.com/support-forums/software-os/f/4997/t/20008264

en.community.dell.com/support-forums/laptop/f/3518/p/19666394/20898193

en.community.dell.com/support-forums/software-os/f/4997/t/20008264

My issue with this, aside from the main problem, is that this seems to be a manufacturing defect (either firmware or hardware) where a single keystroke renders the computer useless. There was no physical damage done to the computer and it is clear that many others have had the same problem, so I am annoyed that support is requiring me to pay for the repair or replacement.

Is there something that can be done here? I have had this laptop for less than a year and a half with almost no issues, and would have likely continued to run well if not for this problem. I don't think it's reasonable for me to have to cover the cost of what is obviously a defect that has been present in these systems since release, especially if it means having to wait however many days/weeks for the part to be available again.

Thanks in advance for any help.