Elastic Beanstalk application failing to deploy - existing application seemingly broken

We've been using EB for about a year, our main backend guy is not working with us at the moment. I've been deploying without any issues for the last 2 months, and today when I've tried to deploy I'm seeing this:

INFO: Environment update is starting. INFO: Deploying new version to instance(s). ERROR: [Instance: i-dc773612,i-4073a981] Command failed on instance. Return code: 1 Output: [CMD-AppDeploy/AppDeployStage0/InfraWriteApp2] command failed with error code 1: Error occurred during build: Command 01downloadVersion failed. INFO: Command execution completed on all instances. Summary: [Successful: 0, Failed: 2]. ERROR: [Instance: i-dc773612] Command failed on instance. Return code: 1 Output: [CMD-AppDeploy/AppDeployStage1/AppDeployEnactHook/01_flip.sh] command failed with error code 1: /opt/elasticbeanstalk/hooks/appdeploy/enact/01_flip.sh ++ /opt/elasticbeanstalk/bin/get-config container -k app_staging_dir + EB_APP_STAGING_DIR=/var/app/ondeck ++ /opt/elasticbeanstalk/bin/get-config container -k app_deploy_dir + EB_APP_DEPLOY_DIR=/var/app/current + '[' -d /var/app/current ']' + mv /var/app/current /var/app/current.old + mv /var/app/ondeck /var/app/current mv: cannot stat ‘/var/app/ondeck’: No such file or directory. INFO: Command execution completed on 1 of 2 instances in environment. ERROR: [Instance: i-4073a981] Command failed on instance. Return code: 1 Output: [CMD-AppDeploy/AppDeployStage1/AppDeployEnactHook/01_flip.sh] command failed with error code 1: /opt/elasticbeanstalk/hooks/appdeploy/enact/01_flip.sh ++ /opt/elasticbeanstalk/bin/get-config container -k app_staging_dir + EB_APP_STAGING_DIR=/var/app/ondeck ++ /opt/elasticbeanstalk/bin/get-config container -k app_deploy_dir + EB_APP_DEPLOY_DIR=/var/app/current + '[' -d /var/app/current ']' + mv /var/app/current /var/app/current.old + mv /var/app/ondeck /var/app/current mv: cannot stat ‘/var/app/ondeck’: No such file or directory. INFO: Command execution completed on 2 of 2 instances in environment. INFO: Command execution completed on all instances. Summary: [Successful: 0, Failed: 2]. INFO: New application version was deployed to running EC2 instances. ERROR: Update environment operation is complete, but with errors. For more information, see troubleshooting documentation. ERROR: Update environment operation is complete, but with errors. For more information, see troubleshooting documentation.

I have no idea why, as far as I can tell I've committed/deployed everything as I normally would. I see the latest commit when I go into 'Application Versions' - and it would appear that is is deployed (it has the environment name next to the commit in the Deployed To column). However my mobile applications are no longer able to connect to the PHP files on the server, they keep getting 403 forbidden - even on files which were not changed in the last commit. It's as if the application is not there since the deploy failed.

Where should I go from here?