IAP firmware upgrade without Ethernet link

I have an IA Realport with firmware IAP Version 82000770_G2 09/24/2008.
The Link led is permanently on so that I cannot establish communication via Ethernet link. I suppose that the firmware too new and it is not compatible with my hardware. I want to downgrade the firmware to 82000770_G1.
I can logon on the Shell of the IAP via the RS232 port. How can I dowload the firmware via the Shell?

The Link LED should remain on when connected via hard-wired ethernet. In other words, this is correct behavior.

Are you able to ping the IP address from the unit?

According to the following knowledge base article, the only way to update the firmware in these units is from the web interface:

http://knowledge.digi.com/articles/Knowledge_Base_Article/Digi-One-IA-IAP-Device-Server-Troubleshooting

Have you tried factory resetting the unit to see if communication re-establishes?

Sorry, but according to my observation the Link LED is off when the hard-wired ethernet is plugged. Another unit with firmware 82000770_G1 03/13/2008 shows Link LED off when it works through Ethernet.
On the Shell with command set config I can see that the IP address is 0.0.0.0. So that I cannot ping it.
I factory reset the unit several times.
The config I can see:
Digi One IAP Version 82000770_G2 09/24/2008

Copyright 1990-2008 Digi International. All Rights Reserved.

hostname : domain :

ip : 0.0.0.0 submask : 0.0.0.0

gateway (LAN) : 0.0.0.0 dns1 : 0.0.0.0

dns2 : 0.0.0.0 dns3 : 0.0.0.0

MAC address : 00:40:9d:23:34:37 interface : ethernet

sockets : 2000 (base) icmp redirects : ignore

dhcp : on optimize : latency

realport : 771 securerealport : 1027

save : on tbreak : std

boothost : 0.0.0.0 bootfile :

tftpboot : no

RARP : on Ping-ARP : on

rpkeepalives : on cache dns : on

rpexclusive : off

Can I set the IP address via serial link?
I cannot set it by arp command because of the lack of link. IAP does not accept any information via Ethernet.

The set ethernet command from shell gives:
thernet status

The Ethernet Lan is: Activated
Link : down
Speed : (set to auto)
Duplex : (set to half)

No link partner.

Sounds like this unit has a bad ethernet port and is in need of repair. I recommend reaching out to Digi Tech. Support to pursue this.