Ericsson MD110 doesn't start

[francescod]

Goodmorning everyone
I have a problem with an Ericsson MD110 PBX with 1 LIM and 2 MAG version CXP1010015/5/BC11SP11/R1A.
After turning on the PBX and connecting the LPU Board display, the system shows various error codes (28xx, 31xx, 32xx, etc ...)and does not start. The telephones remain off and without tone, incoming calls do not arrive.
I have already replaced LSU, LPU, DSU, RG5DC, NIU to no avail. I would like to try to change the back-panel but the one I have in stock is the type BFD 761 17/1 R1A, while the one currently installed is the type BFD 761 07/1 R1B, are they compatible?
If I wanted to restart the PBX excluding the line interfaces, is there a sequence of operations to follow? Thank you all for the suggestions you will give me.

 

[jco62]

when the display is running what does the last display show
20 30 40 xx the 70 xx then 80 and so on
does it go through 80xx then 99 then 101 then 104
does it start all over again
if the display is not showing 101/104/111 then your system has not loaded and your files are not loading from your relvol/hdu

 

[francescod]

Case solved like this:
1) Removed all cards from MAG1
2) DSU in MAG1 disconnected from LSU in MAG0
3) Restarted and, in the meantime, inserted RG5DC in MAG1 and switched on of the latter. When the MAG1 RG5DC was switched on, there was a noise similar to a relay that is energized continuously and therefore the RG5DC was replaced
4) When code 104 was displayed on the LPU Board Display, MAG1 was reconnected to MAG0 and the cards were inserted one at a time.
After these operations the PBX has resumed normal operation.
Thanks everyone for the help.