This Dyson battery started blinking red for ever. So here what I found in this battery of Dyson. I suppose it is the same on pretty much all Dyson Vacuum Cleaners like the Dyson V10 or Dyson V11. I think this one was a Dyson V8.
The cells are 18650 Li-Ion Cells. I measured the voltage of the cells and it was fine at 3.9Volts per cell so completely acceptable but still the battery was not charging anymore. This is a waste of money, a waste of resource from Dyson to create trash from a fine working battery pack for this Dyson V8.
The red Led of the Dyson Battery is blinking. I could not find a way to reset it.
Had to break it to get to the Li-Ion Cells.