Fix the wall-mounting bracket on embedded box with two M4x30 screws.
Mark the two holes of the mounting bracket on the wall.
Take down two M4x30 screws and remove the wall-mounting bracket.
Use a drill bit with 5 mm diameter to make two 25 mm depth holes in the marked positions.
Insert two screw dowels into the holes.
Fix the wall-mounting bracket with two ST4x20 screws and two M4x30 screws.
Installation of back cover
For convenient wiring, hang R20A on the wall mounting bracket with rope.
Make cables go through the back cover, connecting to the corresponding interfaces of the main board.
Fasten the back cover with four M2.5x6 screws, then fix four wall mounting screws on the back of R20A.
Select a suitable size rubber plug to push all the cables into the back cover. Fix cable locking plate to the back cover with two M2.5x6 screws.
Insert the four wall-mounting screws on the device into the corresponding holes on the mounting bracket, and then press down to slide the wall-mounting screws into the groove. Then use the allen wrench to tighten the device with two M3x6 screws.
After successful installation, check stability of the device.