With all the heavy rain we have had recently, its plausable it earth leakage or other, caused by water getting into the charger or consumer unit.
Not using silicone when screwing the unit/s to the wall, will always leave potential for water to track throgh.
You could, but only if confident turn off power to the consumer unit, take cover of this, along with charger and use an extension and hair dryer to dspl and dry any water/moisture from about 8″ away. It will likely dry up when the weather gets better however, if water is getting in, it will always find its way in on bad days, so longterm solution is contact the installer or Ohme and get them do the job properly.
The other isa lazy / faulty RCD and highly unlikely a damaged cable, but my money is with above on this one as best guess.
You could always try charge at a friends or neighbours for an hour or so to prove the point.