Dometic rm3862 getting no power

Sounds like a blown fuse.
You should have a 12 volt DC distribution panel. It is commonly located adjacent to the 120 volt circuit breakers behind a metal cover held in place by a thumb screw. Test fuses with a 12 volt test light or volt meter.
Make and model of rig?

Look on the side of the metal cover of the burner flue tube. There should be a Snap disc with 2 wires. THAT if tripped or bad will not allow 12 volt power to the control board. You wasted money on the Dino board. Doug

PS. 120 power is only for the 120 heat element. Nothing else as the controls are all 12 volt

Follow the 12VDC+ (RED Wires)
At Terminal Block (item K)
To Thermal Fuse (item Y....near burner)
To Thermofuse (item U...switch on burner stack)
To J4 terminal on Circuit Board

Check that the 12VDC- (Black Wire)
from Terminal Block to Ground is clean and tight

IF you have 12VDC+ at J4 Terminal then check the 3A fuse...far left...is good (test for 12VDC on both sides of fuse...not just look at it

Wiring Diagram



As for that Dino P-711
Did your Original board part number start with '385' OR '293'??
Not a correct replacement for Black Box '385' boards