Hi, Rids,
That code refer,s to a DC power fault,
1 Check fuse 2 on the inner control panel it's the middle fuse rated at 500 ma.
2 check for mains voltage across primary coil, if no voltage present check for ac voltage at the ac terminals of contactor coil, if you have volts replace coil if not replace controller.
3 if you had ac volts at primary winding, check for ac volts across secondary winding they should be opprox 2.5v x no of cells,still ac. If no suspect transformer winding yes move on to 4.
4 check for same voltage at ac terminals of rectifier if yes replace rectifier if no check associated wiring.
If your not an experienced electrician My advice is don't go inside this charger get a charger engineer in to do the work.