Having trouble getting a new SD card for the updated Raspberry Pi 4. "No boot block"

Added the 1v5dc bus to power the lights in the signal towers (when installed). Marked the first cut of where the signal towers will go to know where to put connector blocks in the 1v5dc bus. Wanted to get the bus on the bottom of the wiring.

Added 1v5dc "power supply" to 5v and 15v supplies. Added hardware section for DC Power. I am using a relay to connect the battery when the 5v comes on. 

Doing research to find horns for the servos along with ways to connect the control wire to the servo. I don't want to cut and bind the wire. If I make a mistake it could damage a $58 signal tower.

Added a new section "Design Considerations", I keep having random thoughts driving 50 miles to the store, watching my new puppy 'do her thing' and need one place to keep track of them.

Looking at the stack of HATs on top of the Raspberry it is obvious that the Unicorn HAT can't usefully be directly attached if the Raspberry is mounted under the layout with all the servos/signals attached. What is needed is a cable to rap around the edge of the layout so the Unicorn can be on top until the signals get added in Phase II

Raspberry Pi with PWM HAT, Bonnets and Unicorn HAT HD