Washed the Seat and decided my Honda was boggin despite having been the garage for weeks, but no the battery was flat, so I coupled the battery charger and went to do something else, back after 4 hours still nothing doing, realised that with the charger attached even the interior light wasn’t coming on. Rummaged in the garage and found an old school 40+year old non intelligent charger, coupled this and success, seems modern chargers won’t recognise a completely flat battery and so doesn’t know it should be charging, after a couple of hours the Honda battery had enough charge for me couple in the newer one and left it coupled overnight, all ok this morning. Hope this might save someone the same problem again.