I probably have the same Freightliner chassis as your coach. You need really good batteries to crank the engine. I also think you have a battery problem. If those batteries were flat for 7 months, you may have good voltage but not enough amperage available to crank the engine.
Have you tried jumper cables from an operating vehicle to help boost the available amperage?
You can get some expert help for free. Write down the last 6 digits of your VIN number. Then call the Freightliner Help Desk. It's a free service. 1 800 385-4357. They have the build documents for your chassis, and can give you troubleshooting tips. They have been very helpful for me.
Good luck, and let us know the outcome.
Fred