Strategies for debugging AWS connectivity issues

I am having trouble getting my AWS-hosted snowflake-loader-server talking to my snowflake instance – credential issues.

Short of generating events, observing the CloudWatch logs, destroying the stack, making changes, and re-deploying the stack (through Terraform), is there a way to check this more directly?

"EC2 Instance Connect is unable to connect to your instance. " I tried using EC2 connect as a first try to see if I could log in and start or stop things directly. Is there a way to redeploy a single service (the snowflake loader) from terraform without having to destroy and rebuild the whole stack?