Sounds like ball on bike was too high and/or not enough tongue weight. Same thing happens on a truck if your trailer tongue is uphill or the trailer weight is not biased towards tow vehicle.
Yes. THis is a stock battery on the left (for my Ducati) and the padded out Shorai.
I run lithium for a couple reasons - the main one is that they crank a lot harder than a lead acid, the other is that they last a very long time and don't need to be sitting on a trickle charger. Some folks...
Lighter yes. Some are not smaller, cases made to mimic other lead acid batteries. Some like the Shorai are very small and you pad them out with foam stickers.
OK - now that you are back in neutral, sounds like you have a plan.
FWIW - clearly your tinnitus is worse than mine, but music in the background has always helped me ignore it. Had it since I was 22 - summer job where I had a Hughes 500 helicopter landing and taking off next to my head every...
I would ignore the neutral light. Just push it down to 1st with your hand, push a few times to make sure. Then pull up super gentle. Super easy to pull through neutral to 2nd with engine off.
Ooh, I like that. Did you swap the fill and drain plugs? I wonder if the (longer) drain plug contacts the ring gear if you put it in the fill?
Easy check. Remove fill plug and see if wheel spins.
Seems unlikely that high oil would cause the wheel to not turn.
1) I would make sure rear brake is not seized
2) Do as Ross suggested, put it on ground and rock it in neutral
3) pull in clutch and see if it moves
No offense, but you seem like you might be a tad over your head mechanically...
Just in case you don't know. Do not jump off a running car battery. Car off is the only sorta safe way. Although a car battery is capable of providing enough amps to blow the mc battery up if there is an internal problem.