My old MacBook was sitting on the shelf, and I didn't notice that its MagSafe cord had come unplugged, allowing the battery to deep discharge. The computer recognizes the battery (so it can read out the total capacity, charge cycles, serial number, etc), but will not charge it. Measuring the external battery terminals showed 0V (so presumably it must be triggered by a signal), opening the battery itself and measuring across the only two large solder joints on the board (labeled VG and VP) shows 3.8V. The whole battery is nominal 10.8V, and the six cells inside are labeled 3.7V. It's hard to be sure about the topology without destructive disassembly, but as best I can tell, it's three pairs of paralleled cells, in series, with two thermistors in between the stacks.
This picture indicates two solder joints for the cell junctions:
https://forums.macrumors.com/attachments/a1181-battery-board-jpg.433649/ Measuring from VG to the 2/3 junction shows 3.8V (actually a few mV higher than between VG and VP), and VG to the 1/2 junction measures 2.35V. This makes me think that cell pair 1 is at 2.35V, cell pair 2 at 1.45V, and cell pair 3 at zero (it measures -43mV actually).
Here's someone else's pix of the insides of this battery model:
https://www.ifixit.com/Teardown/MacBook+Core+2+Duo+Rechargeable+Battery+Teardown/5173Can I wake this battery up by applying a charge voltage (10.8V?) directly to the cells for a few mins with a bench PSU, just long enough to get them above whatever the controller's threshold is? Or is that just asking to set my house on fire?