Here's what we know:
* Mental health struggles: Accounts suggest he had a breakdown, possibly triggered by his intense religious devotion. He entered a monastery shortly before his death and is said to have spent his last years in a near catatonic state.
* Possible causes: Some historians suggest he might have suffered from a medical condition like epilepsy or a form of schizophrenia, but this is speculative.
* Lack of precise information: No official record of his death exists, only the date and the fact that he was buried at the monastery.
It's important to note that the understanding of mental health during the 15th century was very different from today. While it's impossible to definitively diagnose him, his mental state played a significant role in his final years.