Apologies in advance of this is the wrong subreddit, but I am lost and need a little help with a Juniper SRX240 and an Extreme Summit X440.

Long story short, I got a Juniper firewall and a handful of Summit X440-48P's. I have no clue if they've been wiped of any sensitive info/config data (not sure what may be on them that could be sensitive info), I can't bother the people who were trashing them, and I want to make sure they are wiped before I try to sell them. But I've never the messed with this stuff and I'm lost after reading through the documentation.

I'm assuming I need to connect to the console port on the devices to begin communicating with it via Telnet (is the web UI accessible through this port as well), but I'm not sure if a regular Ethernet connection works, or if I need a cable with a different pinout, an Ethernet to serial adapter, or something non-standard. I found a pinout for the cable connecting to the console connection on the Juniper at least, but am not experienced enough on my own to figure out if what I have laying around (standard Ethernet cables and one random serial/Ethernet cable with unknown pinout) will work or not. I'm mostly afraid of shorting something and breaking stuff.

I'm just trying to figure out how to connect to these devices and check to see if they're wiped/reset and void of any sensitive data and okay to sell. Any and all help would be MASSIVELY appreciated.