It seems there's something wrong happened when the lamp tried to connect to your router.
Could you have a try with:
1、Setup a hotspot with your phone with the same SSID and password with your router;
2、Turn off your touter and connect your lamp to the hotspot；
3、After connection, turn off your hotspot and turn on your router;
4、Wait for a few minute to see if the lamp can connect to your router automatically;
If no, please let us know which router do you have?