First, have you had a recent update to your Bosch firmware? Just thinking that may be the first thing I would look at. Second, do you charge the battery on the bike? Have you tried removing the battery and charging directly to the battery, bypassing the bikes wiring?
The next set of thoughts are blue sky thinking from someone who knows a little about battery management systems but, admittedly, not everything. Especially when it comes to the Bosch system. I have searched for a teardown on the Bosch battery, to no avail (perhaps one of the EBR members has some info). The following is what I've learned about the Tesla battery management system.
Each cell (of approximately 6800 to 8000 cells, depending on model) is supplied with power for charging via a very precise diameter wire that will conduct the necessary current for charging. However, if a particular cells' internal resistance changes, due to physical or chemical damage, this wire will act like a fuse and short, thus decoupling the faulty cell from the rest of that subgroup of cells. The overall battery is degraded, yes, but only by a small amount (especially when you're talking thousands of cells in a power pack).
This leads me to this line of thought: is the Bosch battery similar to that of Tesla? And if the operation is the same, could your battery have been damaged in the fall, causing the permanent (and safe) decoupling of some percentage of the cells?
Again, just tossing it out for discussion.
