Second prototype made several design changes - Switched from Pi Zero W to Pi 3B+, Required some serious slimming down of the PI. Used better battery and charge circuit, Routed the keyboard PCB in one piece, modified button design to include routed letters and orientation tabs and 3D printed cage to keep buttons aligned. Slightly changed button positions and added indentations in the back of the case to improve ergonomics.
Discovered an issue with the power circuit. The USB power bank board shuts itself down when no power is being drawn, it has a button that will wake it up, so I wired a second switch beside the ATXraspi power switch that is activated by the button at the top of the case, this requires two presses to turn the unit on, first press turns on the power, second press turns on the ATXraspi which powers the Raspberry Pi.
The problem is that while the USB power bank board will consistently come on, sometimes the ATXRaspi will not.. I discovered that by shorting the power input to the ATXRaspi while the USB power bank was off that I was able to make everything start working normally again. Since this problem is intermittent, I added a reset switch to the bottom of the case via a small pin sized hole with a switch that shorts the ATXraspi input when the issue occurs.