If you see no other problems the blinking ODU LED on the PoE alone does not necessarily indicate a problem. It indicates the current consumption is not what would be considered normal. It wouldn't hurt to check the cable with a cable tester to ensure there are no shorts.
If the Apex is not powering up or rebooting and both cables are in use, try disconnecting one of the Ethernet cables. The Apex can be powered over the Data or the Management port. If the problem is resolved with only one cable connected, likely the Apex has internal component damage and must be returned for repair.
It would not hurt to check the cable by powering the Apex over the opposite cable and/or checking/validating both cables with a cable tester.