There was one idea I was toying with over the weekend, but have not yet looked into it any deeper.

The way charging-by-flasher works (or actually the whole flashing thing works) is following:

• 1. the flasher loads a small kernel image to the device (called APE algorithm for some obscure reason...?)
  The APE algorithm has an included initramfs that contains the software to flash the device and also a BME implementation that can charge the device if needed
• 2. when the APE is loaded, it either charges the device f under 11% capacity and reports the charging back to the flasher, or it flashes the images transferred down from the flasher

Now, to my knowledge the sources of the APE image have not been published, but as it is a linux implementation it should be gotten from Nokia if somebody just would politely ask about it.

What could be implemented:
If the minimal configuration for charging the device could be determined then it would be no-brainer to make a jumpstarter image that could be started like flasher-charging, but something that does not flash the device, just charges it up to 100% or whatever required.

Additionally I could then implement the charging algorithm in ubiboot, so that would not drain the battery and could be used to jumpstart it if in need.