Yamaha sub with bar speakers, when turn on power, 3 seconds it turn off, again the same every time.

[J.mullane]

Yamaha sub send bar speakers, when turn power on, 3 seconds it turn off, same everytime.

 

[Martaine2005]

There must be a short circuit somewhere. Double check the speaker wires. Even a single strand will short it out.
Or it’s a little more involved with either power supply or output components.
Probably the latter.

Martin