Fully charged or overcharged battery may have given you misleading revs. Not hard to check the timing marks of cam to engine though.

If the chain or timing let go while the engine was reving high things will not be good. If it went on the attempted restart it may not be that bad. Until you have a look it is all subjective.

I would cease trying to restart an the old biodiesel in any event. That will probably will cause even more problems. The whole fuel system should be cleaned out.