I solved my problem; it may not be the same as yours. This was the symptom in my case: I was able to download the IOS via tftp from rommon mode.The ASA would load the image into memory and proceed to this point:
Copyright (c) 1996-2010 by Cisco Systems, Inc.
Restricted Rights Legend
Use, duplication, or disclosure by the Government is
subject to restrictions as set forth in subparagraph
(c) of the Commercial Computer Software - Restricted
Rights clause at FAR sec. 52.227-19 and subparagraph
(c) (1) (ii) of the Rights in Technical Data and Computer
Software clause at DFARS sec. 252.227-7013.
Cisco Systems, Inc.
170 West Tasman Drive
San Jose, California 95134-1706
It would stop there and no prompt would be presented and there was no ability to enter any commands or move on. The important part follows. In the process of loading the image and while booting the asa lists hardware and stuff and you may see this message just prior to the 'Cisco Systems' logo that looks like a suspension bridge:
i2c_write_byte_w_suspend() error, slot = 0x0, device = 0x40, address = 26 byte count = 1. Reason: I2C_UNPOPULATED_ERROR
I copied that message from the attachment from aminulnt above called boot seq.txt. but it is exactly what I saw in my case so I think this fix would work for aminulnt. If you see that message in your output then you likely have the same problem. This is a hardware problem but I was able to fix it. I am not an electronics technician so I gambled a little because I have no service contract and these babies ain't cheap. It took a long time to find a clue on the Internet but this problem results from an IC chip on the ASA motherboard which controls the PoE (power over ethernet) which is available on ports 6 and 7. There should be a tiny black label saying 'power over ethernet' on your ASA over those 2 ports. Evidently there was either a bad run of these chips or they came from different manufacturers because this problem is not that rare. The UNPOPULATED error is a reference to that bad PoE controller. The chip is somewhat hard to buy but they are out there. It is an SMD (surface mounted device) which requires desoldering and soldering in a new one. It is not difficult if you have ever soldered and have proper soldering equipment, It is a small chip, physically about the size of these five x"s: xxxxx and has about 40 legs, so though small it is not extremely tiny as chips go. I removed and replaced that chip and my asa is working fine again.
