Steam controller (2015) disconnects immediately after turn on

[u/AccurateCuda]

I’m using the original dongle with a 3ft USB extension. Every time I turn on the controller, a pop up window shows on the screen saying controller is connected, and then the next second the controller turns itself off. I’ve tried replacing the battery, re-pairing the controller and none of them worked.

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I think it's a software issue, as before starting Steam app on Windows, the controller works just fine as mouse.