TPS65217: SYS output falls from 5V to 1.5V

Part Number: TPS65217

My customer is using the TPS65217, the schematic is a copy of the beagle bone. The SYS output should be 5V, they are seeing this rail fall to 1.5V. This happens on two occasions:

1. Immediately on power up
2. After several hours of operation

Have we seen a similar issue before? Given that this rail powers all the other rails, what would you suggest we test/probe to better understand the root cause?

Thanks,
Nick