The battery problem could be of greater significance if it is related to a very serious flight test event.
Boeing had time and opportunity to investigate and rectify the flight test fault, thus if the current problems are similar this might suggest that either the fix doesn’t work or that the original problem was not sufficiently understood. Neither of which inspire the much needed confidence, nor aid any forecast for a quick resolution, particularly as there was a significant delay in the flight test programme due to the electrical fire.