Why won’t my HK Onyx 6 speaker turn on?

Hi @jab109,

Check if there's 19V DC at the output plug of the charger, in case of a faulty charger or charger cable

If the charger/charger cable is OK then here's a teardown video that will help so that you can disassemble the speaker and check if the DC In (power input) jack is OK and then initially check for any obvious problems on the systemboard e.g. burnt out or heat stressed components

If nothing is obvious then unfortunately as HK doesn't release the schematics or service manuals for their products, you may just have to start by tracing out and testing the power supply path on the board