If you want to install HDDs for your RLN36, please check the following steps.
Step 1. Remove the screws of the NVR with a screwdriver and open the outer case.
Step 2. Find the sets of wires to install the hard drives.
Step 3. Flip the NVR over, locate the screw holes and screw the HDD to the back of the NVR.
Step 4. Install other HDDs in a similar way.
Step 5. Put the screws back on the NVR and tighten them.