Even though you took it apart once, try taking it apart again and give it another real good rinse and wipe-out just in case there's a little piece of sand down the impeller-well where it's hard to see. Sometimes that's all it takes.
That said, it sounds like a defect. The first power on partially burned something up on the inside. Something like that.
Second break down and clean out (and used some canned air) seemed to have fixed whatever the issue was. Since then it has gone through several power on/off cycles with me feeding and has been doing fine.