FAS2220 sounds like a old filer (end-of-life), I last came across it in 2013, must be Data ontap 7-mode ?
Anyway, you mentioned it is decomissioned - Do you have any information about 'what level of decomissioning was done' ? was it simply shutdown keeping all the config as is, including IPs. Or was it simply wiped, if so then HA is not configured (licensed etc) ?
If you cannot reach your filer via ssh@e0M address/Management IP, then the only option is to pysically connect to filer via Console connection and power-it up and see what is it come up with ? That's perhaps the only way you can get to a state from where you can go through initial setup and re-configure it as the way you want it for personal use.