I would go for cleaning the battery terminals first up and the ground to the case. See if that sorts it. Then if no bueno you can hook up a battery via jumpers cables and see if that sorts it.
It is most likely a connection issue if it just happened one day and the battery was not sitting for ages un used. Start with the easy stuff like above. If problems then you will have to open ebox, or, ghetto fix may be to open ebox cap (behind rear cylinder) get a friend to help you stand ski up and see if any water comes out of ebox, if not good, spray it full of wd40 and leave it to soak. See what happens then. This worked for me last season at the beach. Haven't taken it apart since......
It is most likely a connection issue if it just happened one day and the battery was not sitting for ages un used. Start with the easy stuff like above. If problems then you will have to open ebox, or, ghetto fix may be to open ebox cap (behind rear cylinder) get a friend to help you stand ski up and see if any water comes out of ebox, if not good, spray it full of wd40 and leave it to soak. See what happens then. This worked for me last season at the beach. Haven't taken it apart since......