Hello,
Please try the following processure:
Get into rommom mode and then try to upload an ASA image from a TFTP server
1. rommon #0> PORT=Ethernet0/0
Ethernet0/0
Link is UP
MAC Address: 001b.d554.512a
2. rommon #1> ADDRESS=10.10.10.1
3. rommon #2> SERVER=10.10.10.2
4. rommon #3> GATEWAY=10.10.10.254
5. rommon #4> IMAGE=tfpt://10.10.10.2/xxxxxx.bin
6. rommon #4> TFTP
Then if you can get this ASA up, copy the configuration stored in flash to the TFTP server ( backup) and finally you can copy it to running-configuration.
Remember to set the image into the ASA :
boot system flash:xxxxxx.bin
Regards,
Julio
Julio Carvajal
Senior Network Security and Core Specialist
CCIE #42930, 2xCCNP, JNCIP-SEC