Last winter, with snow falling at a foot a day rate, I was forced to switch out my batteries. Due to the weather conditions, worried about the delivery man getting stuck in his two wheel drive, I did notice the small note on my Vanner Battery Equalizer Voltmaster Model 60-20A (run a 24 volt step-down to a 12 volt system) , suggesting to avoid Reverse Polarity damage I would need to disconnect the Ground Terminal first. As you likely surmised I failed to do so and the result is that I lost my DC service.
My question to you is: what damage did I do the whole system (Equalizer, Inverter, and Power Center) and what do I need to do to repair it?
Hard to say what may have been damaged, but I do not think it is as bad as you expect. There is the possibility that the downstream 12 volt appliances may have been connected with 24 volt power, but most inverters have fuses or other safety circuits to shut them down if this they are connected to the wrong voltage or reversed polarity.
I would however, expect that any 12 volt lights may be toast. Bottom line, you will need to check everything out before starting up again.
Let us know how it turned out,