If that's the case, then J5p11 is the Power Good signal that keeps the Top board powered up and turned on after Guide is released. It's also responsible for turning off the controller, so no power on that line means the controller will not stay on. Either there is an issue at J5p11, the trace to the MCU, the MCU connection U1p83 or the MCU itself.
The 1537 MCU board schematic is also in that thread.