HP ENVY x360 Laptop - 15m-ed0023dx won't turn on

[techneer]

Recently my Hp Envy x360 15m-ed0023dx laptop wouldn't turn on. I popped open the back cover for a look and didn't see anything suspicious. I decided to try a new power cord and power jack, even thought the original ones tested okay. That had no effect. I tried disconnecting everything but the necessary components: the keyboard, touchpad, screen and fan. No luck. I tried a new battery. Also no luck. I decided to try a replacement motherboard. No luck. Second replacement motherboard AND keyboard/topcase. No luck. I noticed that the sellers were marking certain pins on the keyboard motherboard connector, so I  jumpered them and was able to start the computer without the screen attached (completely separated from the screen). I was able to do this over and over, adding one component at a time to test for start, and was able to attach an external monitor to access the computer, but whenever I just position the topcase to the hinges (as if I were going to attach the screen to the topcase), the computer won't start. Bear in mind, there is no power or connections attached to the screen. Just positioning the topcase to the screen for hinge attachment will prevent the computer from starting.
I scoured the PDF of the service manual for any info or instructions regarding special procedures for attaching the screen to the topcase-keyboard/motherboard assy, but could find nothing to explain the very odd and baffling results that I am experiencing. If you have the same issue, I suggest disconnecting the topcase/motherboard from the screen and let it sit for awhile. Then, while apart from the screen, jumper pins 13 from the right and 14 (or 13) from the left on the keyboard connector on the motherboard and your computer should start. You may have to remove everything except the fan to get it to start, but it will probably start. Incidentally, pins 13 and 14 from the left are for the power button incorporated in the keyboard. I attached a alligator-clipped jumper cable to two fine-tipped multimeter probes to serve as a jumper.

I also tried placing electrical tape between the hinge connections but that had no effect. I can only conclude that there is something about the hinges or the part of the screen that is juxtoposed to the motherboard when in position for hinge attachment that is interfering with the operation of the computer. I didn't see anything in the service manual to suggest anything that might cause this effect, but this is what I'm experiencing.

[Echo_Lake]

@techneer

Thank you for posting on HP Support Community.
 

That must be hard. Don't worry as I'll be glad to help,
I appreciate your efforts to try and resolve the issue. I understand that your HP notebook is not working correctly. This seems like a hardware issue with the computer. If you have already performed the steps from the document HP Notebook PCs - Computer Does Not Start: https://support.hp.com/in-en/document/c01997899 , No Power or no Boot and the issue persists, it could be a hardware failure.  

I'm sending out a private message to assist you with the next course of action. Please check your Private message icon on the upper right corner of your HP Community profile Next, to your profile Name, you should see a little blue envelope, please click on it or simply click on this link: https://h30434.www3.hp.com/t5/notes/privatenotespage
 

Hope this helps! Keep me posted for further assistance.
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