Awesome; I am glad it helped.
TAKE A BACKUP OF YOUR STACK CONFIG FIRST!!!
First I would do a "stack unconfigure me" or perhaps an "stack unconfigure all"... and a reload. Then I would do an "erase startup-config" followed by a reload.
If it says it is expecting spz10112, I would probably send that over and reload it to see if that message goes away. Then you can put back the bootrom of your choice, and it should go back through the upgrade procedure to upgrade the bootmonitor.
At any rate, it is a bit different being you are running the router firmware SPR08080B I think you said.
On a blank switch, we need to put an IP on an interface that is within the same subnet as your TFTP server or if that TFTP server is on a different subnet, you need to also put a next hop to point to your LAN's default-gateway.
Basically choose an interface like Ethernet 1/1/48 or whatever and put an IP on it within your network on a Layer-3 Interface.
switch# conf t
switch(config)# int e 1/1/48
switch(config-if-e1000-1/1/48)# ip add 10.1.2.3/24
Not needed it the TFTP server is on the SAME LAN... /24 above is for the subnet mask 255.255.255.0 (adjust accordingly to your LAN subnet)
switch(config)# ip route 0.0.0.0/0 10.1.2.1
To Downgrade to 10.1.12 boot monitor that it is expecting:
switch# copy tftp flash 10.1.2.4 spz10112.bin bootrom
Please do a "show flash" to verify it is present before reloading. Sometimes it takes a minute after the copy completes before it is really ready!
Once everything is looking great, you can re-add the device to your stack.
Basically, you would put it back in and reconnect the cables. It is best if it has a matching bootrom and firmware!
Once you connect the stacking cables, if you do not get messages on the terminal that they changed state to UP, you would need to adjust the speed. I do not think this was an issue on the 7450's I dealt with though.
At this point
The entire stack should probably run
stack (config)# hitless-failover enable
Switch you add:
switch(config)# stack enable
Please do this in a maintenance window. If you have hitless-failover, only the new device should reboot. Otherwise the entire stack will likely reboot.
Next, you probably want the MAC addresses of each switch.... top to bottom; since, you want them numbered in order...
Do a "sh stack"
If all is well you will see a ring topology shown.
You are also looking for: "Standby u2 - protocols ready, can failover or manually switch over"
You really do not want to make any changes until everything comes into convergence within the stack. At that point, I would do a "wr mem"
Next to renumber, rerun your "stack secure-setup"
If you have your list of MAC addresses, it can walk you through renumbering all the switches.
Once complete, you want to validate communications
SSH@SWITCH#sh stack connection
Probing the topology. Please wait ...
-4/1| 1 |3/1--4/1| 2 |3/1-
| +---+ +---+ |
trunk probe results: 2 links
Link 1: u1 -- u2, num=1
1: 1/3/1 (P0) <---> 2/4/1 (P1)
Link 2: u1 -- u2, num=1
1: 1/4/1 (P1) <---> 2/3/1 (P0)
CPU to CPU packets are fine between 2 units.
Basically, you are looking that the CPU to CPU packets are okay all around the stack.
If all is great, "wr mem"
At any rate, after a renumber, you may have to change some VLAN memberships etc. Ultimately, though this should be readily repairable.