Forgot admin password

Hi! I’m new with EX4100.

I forgot the admin password. After some trial and error, the dashboard homepage prompt me to reset the device.
I choose the 4 seconds reset method.

"To execute the 4 Second Reset:
With the power on, using a paperclip or narrow tipped pen, press and hold the reset button for at least 4 seconds. The reset process will cause the device to reboot and may take up to 5 minutes to complete. Please wait until the Power LED is solid blue, indicating the device is ready to use.
After 1 hour 30 minutes, LED still blinking in blue. When I ping the ip address of the device, the destination host is unreachable.

Why? Appreciate your help.

Have you tried restart? IP is static or dynamic?

IP address is set to be fixed, but when I restart, it change the network mode to DHCP and the IP address is not the same anymore.