A Cisco ASA5550 was stuck on “Booting system, please wait…” after a power cycle (physically turning off and on, not just a reload). It was impossible to break into ROMMON from here.
After taking the cover off and doing some experimentation, the issue was found to be a faulty DIMM slot. We removed all DIMMs and replaced them one by one. Upon placing a DIMM in slot 1, the firewall failed to boot again. We swapped DIMMs 1 and 2, still no joy.
Removing the DIMM from slot 1 again meant that the firewall came back up.
Solution: If an RMA is going to take time, bring the firewall back up with less memory. Otherwise, swap the thing out straight away as you don’t know what else the power cycle has fried!
You can make your life easier doing the replacement by moving the old ASA’s compact flash card to the external (disk1) slot of the new one. You can then get the right OS on the replacement quickly at least.
NEWASA# copy disk1:/[IOS-image-name.bin] disk0:/[IOS-image-name.bin] NEWASA# boot system disk0:/[IOS-image-name.bin] NEWASA# wr mem
Note: you can copy the running-config on the old ASA to a visible file on CF (eg: copy running-config disk0:/myconfig.cfg), but copying that from disk1 to running-config on the replacement tends to not work very well if you have TACACS config in place. Good old copy and paste from a backup is the way forward.