Got back from a work trip. Opened up my L14 and knew the battery was dead so left plugged into charge via USB-C charger. 6hrs later went to power on laptop but display is blank. When i press the power button i see the keyboard LEDs turn on then off, the toggle switches work, and the battery indicator light is white. Tried pressing and holding the power button for 15 seconds and then powering on. Nothing.
When on I did hear some coil whine from near the CPU on the machine. Other than that I have no idea what could be going on. I did though recently install L14 Bios version 30.
Maybe, in that case the battery should remain separated until you know whether or not the AC power adapter works with the Librem 14. Once we have those results, I can suggest a plan of action for your circumstances at that point.