Could you try factory resetting the AP again and this time, power it up using POE injector and then plug the laptop directly to POE injector's port.
A solid green LED indicates that AP has a IP address (static or DHCP we cannot confirm) and this is why you are not able to ping the default IP address.
Isolating the AP from network will make sure that AP will not get the IP from DHCP after factory reset and default IP will be reachable.
You could also check your switch's ARP table or DHCP lease table, if this AP got an IP address and then try to access it.
I would not suggest opening the AP's cabinet because doing this will void it's warranty. So don't use JTAG to fix it. If even after the factory reset it is not working, then open a support case and get this AP replaced (I hope you have support contract on this AP which is not expired yet).
Syamantak Omer | Community moderator | Staff TSE | CWNA | CCNA | RASZA | RICXI | Follow me at https://linkedin.com/in/syamantak-omer-5949b6124