Can I upgrade raspbian to ROS remotely?

I have 30 rpis deployed in remote parts of Mexico and they are all running Raspbian Jessie. Its not possible to recover them all and upgrade them locally. Can Resin work without its OS, or can it be updated remotely (I have SSH access).

Cheers must have resinOS in order to work. One thing you may be able to do is flash your app onto 30 SD cards and mail those to the locations where the pi’s are and have someone locally swap the SD cards.