I have same problem, Two throttle controller devices based on Cy7c64215-56LTXC hanging on start. Symptoms similar to your. Started from sporadically unknown device. But now completelly not starting.
This SoC even not reading EPROM when starting...
This issue will be difficult to debug, without support from the original manufacturer. Hence, I request you to kindly use the Controller original manufacturer's resources to debug the issue faced.