2014 Freightliner c2 Cummins 6.7 will not start Florida bus ac 72 pass

2014 freight liner c2 school bus powered with cummins engine  6.7 l turbo diesel inline 6 cyl automatic full drum air brakes 72 passengers with large carrier ac system it stopped starting we changed the starter but now will not start it cranks but no start we do not know what is the problem selling as is for more info please call us at 8132172111 or visit tampabusmarket.com