Hey man, I've got a similar issue, Just not the start up problem. I do however know how to change the playback speed. It's a very small potentiometer on the inside just next to the Battery case.
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Get a tiny flat head or a knife and turn it bit by bit, Watch putting the lid back on might mess it up again. Trial and Error.
I've got no fix for the flutter (underwater thing). Hopefully some good cleaning will make the difference.