Attached are the logs that I've found:
Jun 12 19:30:20 ip-10-0-1-207 kibana: {"type":"log","@timestamp":"2019-06-12T23:30:20Z","tags":["error","task_manager"],"pid":12326,"message":"Failed to poll for work: [search_phase_execution_exception] all shards failed :: {"path":"/.kibana_task_manager/_doc/_search","query":{"ignore_unavailable":true},"body":"{\"query\":{\"bool\":{\"must\":[{\"term\":{\"type\":\"task\"}},{\"bool\":{\"must\":[{\"terms\":{\"task.taskType\":[\"maps_telemetry\",\"vis_telemetry\"]}},{\"range\":{\"task.attempts\":{\"lte\":3}}},{\"range\":{\"task.runAt\":{\"lte\":\"now\"}}},{\"range\":{\"kibana.apiVersion\":{\"lte\":1}}}]}}]}},\"size\":10,\"sort\":{\"task.runAt\":{\"order\":\"asc\"}},\"seq_no_primary_term\":true}","statusCode":503,"response":"{\"error\":{\"root_cause\":,\"type\":\"search_phase_execution_exception\",\"reason\":\"all shards failed\",\"phase\":\"query\",\"grouped\":true,\"failed_shards\":},\"status\":503}"}"}
Jun 12 19:30:23 ip-10-0-1-207 kibana: {"type":"log","@timestamp":"2019-06-12T23:30:23Z","tags":["error","task_manager"],"pid":12326,"message":"Failed to poll for work: [search_phase_execution_exception] all shards failed :: {"path":"/.kibana_task_manager/_doc/_search","query":{"ignore_unavailable":true},"body":"{\"query\":{\"bool\":{\"must\":[{\"term\":{\"type\":\"task\"}},{\"bool\":{\"must\":[{\"terms\":{\"task.taskType\":[\"maps_telemetry\",\"vis_telemetry\"]}},{\"range\":{\"task.attempts\":{\"lte\":3}}},{\"range\":{\"task.runAt\":{\"lte\":\"now\"}}},{\"range\":{\"kibana.apiVersion\":{\"lte\":1}}}]}}]}},\"size\":10,\"sort\":{\"task.runAt\":{\"order\":\"asc\"}},\"seq_no_primary_term\":true}","statusCode":503,"response":"{\"error\":{\"root_cause\":,\"type\":\"search_phase_execution_exception\",\"reason\":\"all shards failed\",\"phase\":\"query\",\"grouped\":true,\"failed_shards\":},\"status\":503}"}"}
Jun 12 19:30:26 ip-10-0-1-207 kibana: {"type":"log","@timestamp":"2019-06-12T23:30:26Z","tags":["error","task_manager"],"pid":12326,"message":"Failed to poll for work: [search_phase_execution_exception] all shards failed :: {"path":"/.kibana_task_manager/_doc/_search","query":{"ignore_unavailable":true},"body":"{\"query\":{\"bool\":{\"must\":[{\"term\":{\"type\":\"task\"}},{\"bool\":{\"must\":[{\"terms\":{\"task.taskType\":[\"maps_telemetry\",\"vis_telemetry\"]}},{\"range\":{\"task.attempts\":{\"lte\":3}}},{\"range\":{\"task.runAt\":{\"lte\":\"now\"}}},{\"range\":{\"kibana.apiVersion\":{\"lte\":1}}}]}}]}},\"size\":10,\"sort\":{\"task.runAt\":{\"order\":\"asc\"}},\"seq_no_primary_term\":true}","statusCode":503,"response":"{\"error\":{\"root_cause\":,\"type\":\"search_phase_execution_exception\",\"reason\":\"all shards failed\",\"phase\":\"query\",\"grouped\":true,\"failed_shards\":},\"status\":503}"}"}
[2019-06-12T19:29:05,544][WARN ][logstash.outputs.elasticsearch] Attempted to resurrect connection to dead ES instance, but got an error. {:url=>"http://localhost:9200/", :error_type=>LogStash::Outputs::ElasticSearch::HttpClient::Pool::HostUnreachableError, :error=>"Elasticsearch Unreachable: [http://localhost:9200/][Manticore::SocketException] Connection refused (Connection refused)"}
[2019-06-12T19:29:10,556][WARN ][logstash.outputs.elasticsearch] Attempted to resurrect connection to dead ES instance, but got an error. {:url=>"http://localhost:9200/", :error_type=>LogStash::Outputs::ElasticSearch::HttpClient::Pool::HostUnreachableError, :error=>"Elasticsearch Unreachable: [http://localhost:9200/][Manticore::SocketException] Connection refused (Connection refused)"}
[2019-06-12T19:29:15,621][WARN ][logstash.outputs.elasticsearch] Attempted to resurrect connection to dead ES instance, but got an error. {:url=>"http://localhost:9200/", :error_type=>LogStash::Outputs::ElasticSearch::HttpClient::Pool::BadResponseCodeError, :error=>"Got response code '503' contacting Elasticsearch at URL 'http://localhost:9200/'"}
[2019-06-12T19:29:20,670][WARN ][logstash.outputs.elasticsearch] Restored connection to ES instance {:url=>"http://localhost:9200/"}
Jun 12 18:25:29 ip-10-0-1-207.ec2.internal systemd[1]: Started Elasticsearch.
Jun 12 19:15:28 ip-10-0-1-207.ec2.internal systemd[1]: elasticsearch.service: main process exited, code=exited, status=127/n/a
Jun 12 19:15:28 ip-10-0-1-207.ec2.internal systemd[1]: Unit elasticsearch.service entered failed state.
Jun 12 19:15:28 ip-10-0-1-207.ec2.internal systemd[1]: elasticsearch.service failed.
Jun 12 19:28:48 ip-10-0-1-207.ec2.internal systemd[1]: Started Elasticsearch.