Chosen Solution
I recently replaced the battery in my 9570, using the kit and battery from IFIXIT, along with a new RAM kit from Crucial. Since the replacement, when the laptop goes into hibernation mode, after being left alone, it won’t turn back on unless plugged in. The LED battery indicator light won’t even turn on when this happens. Sometimes the Dell screen will flash, then turn back off. Once its back on, it can be unplugged and it behaves normally.
For possible hardware/firmware cause resetting the BIOS may help. Here is the link to the XPS 15 SErvice Manual (bless HP): https://dl.dell.com/topicspdf/xps-15-957… Page 50 for the actual part - you just need to unplug it for 1 minute Here’s the steps: https://www.dell.com/support/manuals/en-… Of course look at the IFIXIT tear down: Dell XPS 15 9570 Unboxing, Battery & RAM Removal
