Red Light . USB cable cause a Problem

My Cloud OS 3 Personal & Network Attached Storage My Cloud
2

You shouldn’t connect the NAS to a computer using a USB cable! It is not designed to work that way.

A red light indicates a hard problem with the disk. If resets don’t work, you can try to do a soft unbrick. For example:

http://community.wd.com/t5/WD-My-Cloud/How-to-unbrick-a-totally-dead-My-Cloud/m-p/651195/highlight/true#M3848

Otherwise, you will have to RMA the drive.