12 volt rv battery vs 6 volt gc batteries

I took the two Trojan 105 batteries over to the RV shop were I bought them. A previous mechanic had tested them and said they were dead but the place were I bought them from checked them and said they were completely discharged but he said Trojan batteries were the best ones out there and he thought they were still good. He connected them together to form one 12 volt battery and began charging them. I called back about 5 hours later and he said they were still charging but he said when they were so completely drained it usually takes a long time for them to be completely recharged but he still thought they were still good. I mentioned that I had thought about going with two 12 volt batteries and he said he thought I would be making a mistake. He seemed pretty convinced that they were still good but needed to be fully charged. I hope he is right but I don't know what I did wrong to fully discharge them. I'm kind of apprehensive that I may make the same mistake again if they are still good. I'm trying my best to understand the battery procedures on what to do when they are in the trailer while its in storage. My 29-5T has a battery kill switch, a Blue Sky Solar Boost 2000E, 2 120 watt solar panels and I use the stock connection on the roof. My rig came with the stock charge wizard so if any electrical whiz out there knows the best way to handle my storage problem please speak up. I have been very forgetful lately and maybe I did something wrong and I caused my own problem so what I want to do is draw up pictures on what I should do and the order they are done and have also the written procedure with it. I would like to put together a book for everything on it so I have it all organized. If I'm going to use my 5'ver I want to do it right! I'll post the final test results when I find out, maybe tomorrow!
Thanks for all your help
GaryCQ