In order to investigate what caused the "ModelError", you need to check the logs from the model container. Logs from endpoints are emit to "/aws/sagemaker/Endpoints/[EndpointName]". Please check if you see more specific error message there.

For more information where SageMaker emits logs, see this document page: https://docs.aws.amazon.com/sagemaker/latest/dg/logging-cloudwatch.html