The devices don't power on because they require Passive Poe to be configured in port in order to work properly.

According to information provide on links below:

• Passive POE support is not listed in the supported features for EX2300 EX2300 Switch Hardware Guide (juniper.net)
• Passive POE support is not listed in the Hardware Guide for EX2300 https://apps.juniper.net/feature-explorer/parent-feature-info.html?pFKey=1097&pFName=Power%20over%20Ethernet%20(PoE)
• Juniper does not have passive POE-supported hardware, because the Juniper switches only support: Full PoE, Full PoE+ and PoE++ (EX4400 platform)