To factory default your ACP-EL4 you will have to take the following steps:

1.) Set address on pin-out board as follows:

ON 1-3-5-7

OFF 2-4-6-8

2.) Now power controller using a 12v DC power supply.

3.) Leave on for 10 seconds.

4.) Disconnect power.

5.) Now set address back to default ALL set to OFF position. 

The default address is 192.168.0.2

User name= admin

Password= 123456

Please find pictures attached for reference.

Thank you