SystemCore Beta Stuck in Bootloader

I am unable to get SystemCore to boot. When powered, a solid green light is shown, and nothing appears on the LCD screen. The unit does not produce a wifi signal.
Attempted to re-flash the SystemCore with Limelight Hardware Manager in Administrator mode using 2027.0.0-beta14.zip. When the boot button is held down and unit powers on, LHM detects the device and successfuly sends boot data to the unit. It then reboots the unit, and then no longer detects a valid device (no selectable target devices available). A 128MB drive appears in My Computer with a text file indicating it's the bootloader drive. Drivers were installed/reinstalled with no change.

Andrew Kempen recommended checking to verify the CM5 was properly seated. SystemCore was opened up, fully inspected and re-seated in case this was the issue. The LED/LCD board was also reseated with no improvements. A solid red light is shown on the main (breakout?) board when powered on as well as 2 co-located solid green LEDs. Boot button was verified to not be stuck down (clicks freely) when pressed).

Suspect the board is stuck in a bootloader loop, looking for advice on how to restore it. This SystemCore was working normally and even demoed at the FRC Mentor Conference a couple weekends ago, but has not been powered on since.

Start by reviewing the attempted 2027.0.0-beta14.zip reflash with Limelight Hardware Manager, including the boot button sequence and the 128MB bootloader drive. Check the CM5 and LED/LCD board seating details, then reproduce the boot behavior; done means the SystemCore exits the bootloader state, displays on the LCD, and provides a Wi-Fi signal.