Notebook Boot and Lockup

I have an HP ENVY 13-AQ0044NR. I bought this laptop new in December of 2019, so it is out of warranty by just over 4 months now 😞  About a week ago I tried to turn it on but it wouldn't boot. I tried charging it with both the USB C charger and the blue tip (regular) charging cable, neither one would charge it or turn on the indicator light. I took it to a repair shop who couldn't diagnose the issue and found everything internally to be in sound condition. They did an internal reset, which they described to me as disconnecting and reconnecting the internals and it began to boot after that. All was well for about 2 days until it happened again, so I took it back and they internally reset it and still couldn't find anything wrong with it. A day later it happened again, this time I opened it up myself and disconnected ONLY the battery connector, waited 10 seconds, then plugged the laptop in (without the battery connected), and to my surprise, the indicator light turned on, even though it hadn't turned on moments before when I had plugged it in before disconnecting the battery. It booted up just fine on the power cable, so I used it for about 10 minutes before it "died" again while only connected to the power cable. Evidently the battery is not the culprit here. I plugged the battery back in and it still worked just fine when not connected to a power source, but subsequently died not too long after and required another disconnect and reconnect of the battery to be able to boot again. Why could this be happening, and what can I do since my $1000 laptop is failing (conveniently for HP) just 4 months out of my warranty? This is absurd, I certainly won't ever be purchasing devices from HP again.