Cant connect to a pi

Ok, Ive got some second hand pi's, but for the life of me no matter how I try, I can't connect to them.
I know they worked, but the wifi is now different and that's what I want to change, but even direct Ethernet connection they are not coming up.

I know I am doing something wrong, so hit me with it please

Did you load a fresh FPP image onto the SD cards?
What version of FPP? What model Pi?

1. Plug the PI into the network directly with the ethernet connection
2. boot the PI up and give it a couple minutes
3. Open xLights, go to tools FPP Connect and it will search for the FPP instance on the pi.
4. Click the link for the found in the FPP Upload

If it does not find it, that most likely means it is using a static IP different from your own.
1. Attach a monitor to the HDMI and check the screen for the assigned IP address.
2. You will need to adjust your network settings on a device to match the ip settings on the PI. Normally it means using the same ip range x.x.x.? and changing the last part to a different number from the pi, and using a subnet mask of 255.255.255.0 which should work 95% of the time.

if neither of those work you can always make a clean copy of FPP 7.5 and start using that.

I will try that again. No they are in a stand-alone prop and I want to keep it like it is so no new sd cards.

Well a mini breakthrough, I have managed to get 1 of the 3 pins to talk. What I have discovered is that 2 of the 3 believe they are the same ip address. Not sure how or why, but they both displayed "I am ip address 192.168.1.122"
I have the main one with the octo running on the right wifi, time to tackle the next one.
What's the trick with the 3rd one that doesn't have a hdmi port for display?