...
Simplify Isolated DCDC
U4
Original
Charge pump switch regulator
https://www.digikey.ca/en/products/detail/microchip-technology/tc7662beoa713/418710
New Change
U5
Original
New Change
https://electronics.stackexchange.com/questions/582157/alternative-to-optocoupler-in-circuit-design
Inductive coupler
RF coupler
Capacitive coupler
U9
Smaller changes
Removing:
Fan control
Remove fan connector
Remove entire fan control sheet
Thermistor
Remove thermistor connector
Remove entire thermistor sheet
Add jumpers near AND gate to skip it
...