Nintendo Switch Dock Not Responding Fix To Try First

When you place your switch in to the dock, and all you get is a single flash from the green light, then it is highly likely your dock is not broken, it is just in a (software) fault state.
To reset the system back up, follow the below steps:

1) Ensure the Switch console is on the latest software update, or install the lastest update, which can be found in your switch settings under system settings.

2) Press and hold the power button of your switch, then find the Restart option and select it (Not sleep mode).

3) Whilst the switch console is restarting, switch off power supply to the dock unit, wait a few seconds, then switch power back on.

4) Place the switch in the dock, and should now work fine.

If this does not solve your issue, then you may have either damage to your switch charger port, or a defective dock unit.