MK 152 must hold button, speed doesn't decay

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1

My son built an MK 152 at camp, and it has a problem. It was working OK when he came home, but when he tried to screw the battery compartment on to the back, the behavior changed.

Now, when you press the button, the LEDs spin at a constant rate until you release the button, then turn off. If you hold the button, the keep spinning at a high rate.

The seemed like a capacitor problem, and the 1uf capacitor wasn’t reading correctly on a meter, so we replaced it, but no change.

Any suggestions on how to further troubleshoot?

Thanks for any ideas,
Ken

2

Most likely there is a mechanical problem, since the problem started when the battery holder was screwed onto the PCB.
Check if one of the battery holder wires is not perforated by a soldering.
Also: Check for bad/loose/intermittent solderings and make sure none of the solder pads/tracks have released due to mechanical pressure.
If you can provide links to hi-res pics of both sides of the board, then we can also take a look and maybe spot the problem.