OpenSearch stuck at updating service software for months

On updating service software version R20211203-P2, our OpenSearch cluster versioned Elasticsearch 7.4 has remained at 20% status for months. It is unable to proceed onto 'Creating a new environment' stage. Our cluster health is green, and all the nodes are healthy.

According to Why is my Amazon OpenSearch Service domain stuck in the "Processing" state?:

• We have enough free IP addresses in our subnet
• No KMS key is required as our domain is not encrypted
• No pending tasks, CPU and JVM usage are within normal parameters. No index shards are stuck
• Amazon Cognito is not enabled

As we do not have Premium Support with AWS, would AWS OpenSearch team still be able to assist to retry the process?