I had the same happen on my old B8200 - the forerunner to the B2150. The battery cable looked fine, ohmed out fine. But is could not handle any current because of all the corrosion hidden under the insulation. Put a new cable on; motor spun over like new.
H of a thing that you split the tractor in order to see that, now, the motor will turn ... and still do not know what jammed it. Hope you have some other tractor to use while you play with this one... wild journey.
If you have a high power impact gun you might try spinning the engine with that to see if you can duplicate the torque the starter tried to apply to the engine. I assume you checked the ring gear for damage and ensured the flywheel is not cracked at the mount bolts.
Had a kubota tech come over after it was split. He also looked and couldn't find any reason why it did what it did . He looked at everything and said he doesn't see e any problems , suggested I reassemble it , I did and it still turns. Bought all new filters and fluids yesterday , I'm putting them in today. We'll see one is started. He was as baffled as the rest of us.
You may never know. Several theories were mentioned over the last 59 posts (like a loose bolt, a falling part lodged in flywheel teeth, etc. etc.) If it starts and runs normally after you get it back together declare victory and try to forget about it. ... but you won't !!Had a kubota tech come over after it was split. He also looked and couldn't find any reason why it did what it did . He looked at everything and said he doesn't see e any problems , suggested I reassemble it , I did and it still turns. Bought all new filters and fluids yesterday , I'm putting them in today. We'll see one is started. He was as baffled as the rest of us.
