The clutch adjustment is a procedure with more than one place to set tolerances. You need to do as the sheets in the manual say, adjust the clutch lifter, then adjust the cable at the clutch and then the cable end at the handlebar lever. The tolerances are on those sheets. I went back and read this from the start and you said that you checked the fluids. I noticed that you did not change the oil. It is possible, like Dan said, that the plates are stuck together, depending on the condition of the oil that was left in it, how long it sat up not running. Condensation from temperature changes and contaminated oil can cause corrosion on the clutch plate surfaces and cause them to stick together. I would crank the engine to warm it, then drain the oil first to see what comes out of it. Then I would do and engine flush with like two quarts of cheap oil and1 1/2 quarts of automatic trans fluid, let it idle for about 10 minutes, shut it off and let it set for a day or two. Drain the flush mixture out, replace the filter and fill with the proper oil, adjust the clutch by procedure and see what you got. That's what I would do, you might wait and get other recommendations from some of the other guys before deciding. If it doesn't work, you may have to pull the clutch discs to soak, separate and access plate damage. The clutch is a wet clutch and runs in the engine oil so there is no special place for just to add oil for the clutch. If this doesn't work you will already have fresh oil to reuse and a new filter on it when you do get it working.
Sorry Brian, wasn't trying to step on your toes, we obviously were thinking alike.