EC2 Key Pair Issue

Hi AWS,

I have created an EC2 instance and its key pair using terraform code. The terraform code for the same is:

resource "aws_instance" "test_ec2_instance_production" {
  ami                    = var.ami_id
  instance_type          = var.instance_type
  subnet_id              = aws_subnet.public_subnet.0.id
  vpc_security_group_ids = [aws_security_group.test_security.id]
  tags = {
    Name = "${var.default_tags.project_name}-${var.default_tags.environment}-ec2-instance"
  }
  key_name                    = var.generated_key_name
  associate_public_ip_address = true
  monitoring                  = true
}

// Create key-pair for EC2 instance

resource "tls_private_key" "prod_key" {
  algorithm = "RSA"
  rsa_bits  = 4096
}

resource "aws_key_pair" "generated_key" {
  key_name   = var.generated_key_name
  public_key = tls_private_key.prod_key.public_key_openssh
  provisioner "local-exec" {
    command = <<-EOT
      echo '${tls_private_key.prod_key.private_key_pem}' > test-prod-keypair.pem
      chmod 400 test-prod-keypair.pem
    EOT
  }
}

I have generated the keys using the command ssh-keygen -t rsa -m PEM.

Now I am trying to provide the private key in the SSH server configuration setting of Jenkins and I am getting this error: jenkins.plugins.publish_over.BapPublisherException: Failed to connect and initialize SSH connection Message [Auth fail]

Also I am not able to login into the EC2 using SSH connection command as the key is broken and getting this error: ec2-user@ec2-x-xxx-xx-xxx.us-east-2.compute.amazonaws.com: Permission denied (publickey,gssapi-keyex,gssapi-with-mic)

Now the issue is this is a production environment and the key is broken. Is there any way to replace the key with a new one without terminating the instance as long way down I need to have a proper RSA key which I can add in the Jenkins SSH remote host to build my pipeline. Also you know Jenkins don't accept Open SSH key format.

Also I need to know the steps to generate the rsa key and to copy the key file into the .pem file which we are going to use for ssh connection with EC2. Please help!