Geez! I believe I have come to the realization if you want to kill a DNA board, you swap batteries really fast. Sure 99 times out of a 100, nothing bad happens. Then there is that 1% chance. This is the fourth DNA this happened to me in two years and changing batteries fast is what they all have in common.
I popped that battery out and in (why does in and out just sound better?) of that Therion BF 75C two days ago and I can't recall if I vaped after that or not (if I did, it wasn't much). But early this morning I grabbed it and tried to vape it. Absolutely nothing. Strange, that was a damn near a full battery last time I checked. Popped the battery out and checked it with a meter and it said 0.5v. And I thought no way! Maybe this meter finally died. I didn't grab another meter, but I grabbed a charged cell instead and it said 4.14v.
Dang! Maybe it is really the battery. After all, the meter said it is low and the DNA didn't fire up, so I put a charged battery in and the Therion fired right up. Connected EScribe and nothing looked incorrect or anything with EScribe's Device Manager (DM). Ran DM for a couple of hours and nothing looks wrong. Checked that cell that was just sitting on the bench at 0.5v and it bounced back up to 1.74v. Ah that four year old cell that lost about 40% capacity since new which I was just going to write off anyway was fighting for its life (it's an old blue Samsung 25R btw).
I should probably warn anybody who tries what I do in this situation. I highly advisable nobody try this at all. But if you do anyway, first thing is to totally expect the cell may go thermal, meaning that it could burst into flames. Within the first 24 hours is your best bet to bringing it back to life again. Next I read and I never try charging any faster than 100ma (any faster than about 1/10C I'd say or your odds of going thermal greatly increases). Also check outside battery temperature (you can't check inside temperature obviously which would be the best). Any signs whatsoever the battery temperature is increasing from room temperature just stop everything. Hopefully you stopped it in time and it ain't going into thermal runaway, but be prepared if it does.
Well many experts say once you got the voltage up to normal range, you can start increasing the charge current. I generally use about 3.2v as the start of the normal range. Well I got it there and slowing started to increase the charge current. I probably shouldn't have done it, but I pushed it up slowly to 1A. I still see a huge danger of it going thermal at 1A. But it behaved perfectly normal and charged to 4.2v. My charger said it fed 2550mah into it which sounds very impressive for a four year old well used 2500mah cell. But that was from 1.74v, so not so impressive but ain't too bad either. So this cell is on the critical watch for a few days to see how it behaves. So far so good.
I can see why I would for a living thing struggling to save its life and if anything I could do to save it I would. But this is a nonliving battery trying to save its life, so why do I even bother? I should just let the dang thing die! In battery years, it is ready for the graveyard anyway.
Haha... bet you all forgot about the Therion BF 75C, didn't you? Yeah well it ain't doing so well. If you put in a full charged cell and didn't vape on it. It would take 12 hours or more to drain to 3.2v (but it will continue until to drain to at least 0.5v anyway with enough time). So I don't really see any hope of ever taking it off life support. Maybe I should just pull the plug on this mod with only 250 puffs on it.