@yhwang
Hello, apologies for the super late reply, I hope you have got this resolved already.
If anyone experiences the same issue, please confirm the below info:
1. Do you still use the original power adapter? Was there any power cut or bad weather or firmware upgrading before it behaves abnormally?
2. Try to hard reset it by holding the reset button or hole until all the lights flash, then confirm again.
3. Are you able to access its web UI from a browser? What is the hardware and firmware version?
4. When and where did you buy this also? If nothing can make it power on correctly, you may need to contact the local tech support to check the warranty cause the device seems faulty:
https://www.tp-link.com/en/support/contact-technical-support/#Hotline-Support