I am upgrading from a rpi3, to a 4. I moved root to the SD, and am running the OS on an ssd (openhabian).
I thought I just had to insert the sd, and the hard drive to the new pi, and it would work, but I have issues.
ZWave stick is not powering up, hard drive is not powering up, cannot see the rpi on the network even though its patched via ethernet.
Any help is appreciated.
You cant just swap Rpi´s like that. Rpi4 is alot different than Rpi3. Rpi4 require raspbian Buster. I doubt you have that running on your Rpi3.
So you´ll have to make a backup of your Rpi3, and then restore the data onto the Rpi4 after gettting a stock openhabian up running on the Rpi4.
Some Zwave sticks need to be connected through a powered USB2 hub so they do not get detected as USB3 devices.
No need to spending time trying to get the Zwave dongle to work, untill he has the system up running.
Save some time - Do it right first time 
So I’m not an expert, but recently did the same thing. The post at the end summarizes my actions. I did not swap cards, but started from scratch with a full backup from my RPi3.
Bob
Well, I dont know if I can access the current pi to make a backup
Sounds like the best solution is just to buy another 3b+
Is the old RPi3 dead? Your original post just said you were upgrading. If it is dead, getting another RPi3 would be the fastest solution to getting back online.
I’m not sure what is wrong. According to paperui, there are no things…but I currently cannot access via samba, it’s been functional for years. I have our IT people trying to get it to show up on the network list.
Think I’ll just purchase the other pi3 and try that route at this time. Thanks for your assistance. I didn’t realize there was such a difference between the 3 and 4…
Have you tried a different SD card? It’s possible that your original SD card is corrupt.
It all runs of the ssd
Hopefully replacing the RPi3 gets you going again.
Perhaps you can enter your data on the SSD, and that way get a copy of you setup.