Forgot my 2xAA flashlight out in the cold turned on all night. One AA cell dropped to 0.07V and the other one 0.8V. Will the 0.07V cell still charge?
Probably depends on the charger. You can put it on a dumb charger for a few minutes to get it up to a recognizable voltage for a smart charger if need be. I’ve had some that dropped to 0 volts that recovered just fine after a refresh cycle.
“Envelope”? Sure it’s not an Ikea LETTA? 
I’d just let it warm up overnight then try slow-charging it. A reverse-charged cell is probably a goner, but the other one might not be.
^^ My fingers are just too big for these smart phones...... too many spelling errors!
Just noticed the low voltage one jumped to 0.345v already after having it inside for about 30 minutes, so I'll take your advice and let it warm up all night and charge tomorrow thanks.
Thanks and I'm also glad I didn't throw away all my dumb chargers now that I know I can do something like that to bump up the volts.
Just after warning another few more hours at room temps, both batteries are now at 0.9V. I marked these batteries as from amazon and all of my inconsistent batteries are always from amazon. I never ever had any problems with eneloops from costco, always only from amazon.