Need help with an OLD AS/400 3901 150 without access to it

Hello all , my name is Edoardo from Italy and I would like to be part of
this community as an apprentice.

I'm a retrocomputing (as we call it) entusiast and I'm creating a
collection of vintage computers\server (C64 , C128 and also old servers).

I would like to learn RPG into the bare metal so I bought this AS/400 3901
150 from ebay..

They sold me it without cables and without info...

This is not my first time with this sistem as a user because my company
uses IBM i power on daily basis but I would like I to have my own server
(it make you feel a god hahaha).

So.. This is what I was able to do alone:

At the power cord plugged I noticed a 0000BBBB error on display..Internal
Battery is gone..

1) First turn on IPL B N... Result : after an hour of recovery codes (they
for sure turn it off removing the power cord) I obtained a A9002000 -> the
machine needs a terminal I don't own..

2) Second IPL B N after a clean shutdown from panel. This time I put a
cross ethernet cable on it with wireshark on my pc to see if it sends
something from the ethernet. After the boot I started to see ARP packets
from 10.110.1.5 -> bingo I got you !! Here I saw also that the telnet port
was up and also the ftp one plus a 139. I tried an ftp to the IP and the
system responded correctly with hostname the serial number of the machine
!!!
But here I made my first noob mistake: I unplugged the cable to attach my
job laptop wich have the terminal emulator.. On the discovered IP I saw
host unreachable (dough!!).

The network went down only from unplugging the cable...Thank you IBM!

3) In the third attempt I put up a mini network with a spare router on the
discovered subnet and again using wireshark on the other pc (this time with
tn5250j installed). After the IPL I was not able to capture any new packets
from the machine and I got again a A9002000...(grrr)

4)another IPL with a 02 B N on display but the warning lamp is on. Again no
other packet is sent and the host is unreachable...

Sigh sob ! What to do now ? I m here to search for a little help from you.
(Also some manuals wich i cannot find)

Is there a way to enable console again from panel?

I have plenty of time as COVID-19 locked us all home. I can have also
remote skype help.

Thank you all
Edoardo