@OP:
if the unit is used then it is likely that you cannot access it by using the default IP address. HTTPS access is more likely than HTTP access. Use an internal port to connect.
The only way it will work 100% is to access it via the serial console port. There should be a serial cable included with DB9 plug on one side and RJ45 on the other (also known as a Cisco serial cable). Use a terminal program and connect to COM1 with 9600 baud, 8N1. The speed might also be 19200 baud.
Then you have to log in, as " admin" and hopefully without a password.
If the previous owners have installed a password there is a procedure to reset it - search this forum for " password reset" to get the details.
Ede
"Kernel panic: Aiee, killing interrupt handler!"