It shouldn't be harmful if your AirPods have been connected to a Fast Charger. It doesn't sound like your AirPods have charged at all. If you can, try a different charger and cable.
You can also try resetting your AirPods. First, delete your AirPods from your iPhone, go to Settings → Bluetooth → AirPods → Forget This Device. Also open the Find app and remove your AirPods from Devices for a fresh start.
Then, open the lid and hold the pair button on the back of the case inside for approx. 15 seconds until the LED light first flashes orange, then white. If the diode lights up, your AirPods are alive - reconnect them to your iPhone.
If, after trying a different charger and cable - as well as trying to reset your AirPods, you still can't get them to life, then you may need to have an authorized Apple repairer look at them.
Find more information about this here:
AirPods Repair & Service - Apple Support