If I turn them off and then plug them into my boots and press the on button and not release it I can power up to the 4 position but I must not release the pressure on the on button or they each will immediately turn off. In other words no matter what I do I cannot get the 3 battery packs to remain on even a second or two when plugged into my boots.
At no time during charging do the lights flash inappropriately.
These packs are my wife's and have only been used 10 times this year and once all of last year.
It seems to me the packs must now be bad but such a strange coincidence that 3 of the 4 would go bad at the same time.
Any thoughts would be appreciated.