I went for a run today down the beach and found a go pro in the water.I have manage to find out who the owner is by some detective work.It is probably going to take awhile before I can get it back to the owner as he is on a cruise ship.My question is ,will the battery charge up ok ?The reason I ask this is shortly after I found the thing the battery went flat.If it stays flat for a long time it may not be able to be charged.So basically how long can it stay in this state before its battery is kaput?