can't post comments, pardon the intrusion.
you will most likely have to interrupt the bootloader (put it in ROMMON mode) and flash a new image.
it could be nvram corruption (actually, that would seem to indicate a problem in flash).
see: Cisco - Recover the Image on an ASA 5500 Series Security Appliance (PDF)
or it could just be some control message is being misinterpreted. have you tried a telnet/ssh client? but that kinda looks doubtful.
also, try different (lower) baud rates, could just be some settings on the unit, or erase nvram in rommon.
well tbh, i've only dealt with asa devices on 2 occassions. so i just don't know enough about them to say.
i couldn't make any sense of that log file, but looking at it now. it is failing to load the image, at the very end:
eadng romflah.. !. rypochcksm (nchnge): f290c46b337a 5f275f 184120
some checksum error
normal output is
just some more info on erasing flash: erasing/formatting flash should check for/mark bad blocks. additionally, erase marks blocks as 0xFF and reinitializes the filesystem. some of this stuff i just learned today, so bear with me ;p
you can test the filesystem for bad blocks
fsck -test flash. (these are bootloader commands) for a switch, the recovery looks something like
load_helper, copy image over,
boot system flash:filename.
as per the following guide: Recovering Catalyst Fixed Configuration Switches from a Corrupted or Missing Image
bootloader cmd ref: Catalyst 2950 and 2955 Switch Boot Loader Commands
image/filesystem ref: Managing Software Images and Working with Configuration Files on Catalyst Switches
for asa 5500 series: ASA 8.x: Troubleshooting ASA Flash Errors
closest i could get for ASA. i always have issues finding detailed guides for them, so i tend to use the switch/router guides as additional info.