[Zuman]

I have three Bosch 12v tool batteries that won't take a charge. I've watched a bunch of YouTube videos about jump-starting L-ion batteries with a good battery, but that hasn't worked for mine. I've also tried the "rapidly-switching-the-charger-power-on-and-off" approach that supposedly works with NiCads, but no joy there, either.
There was one interesting video about opening the battery case to gain access to the cells and then pressing a release button on the positive end of each cell to reset the cell, but opening the cases is easier said than done (the ones I need to revive don't have the three slots in the base or visible screws).
Has anyone had any success reviving lithium ion batteries for power tools?

[BobM]

You will probbably get a far better answer posting this question on a forum for carpenters, gardeners, people who work with those tools all the time.

[WGH]

Usually dead is dead. I buy a replacement battery and move on with my life.

You can ask at Masters of Finish Trim Carpentry on Facebook and then settle in for some well deserved abuse.
https://www.facebook.com/groups/257296515202295

[FullRangeMan]

Power tools needs alot of amperage from the battery.

[S Clark]

Usually dead is dead. I buy a replacement battery and move on with my life.
[/quoteI

And I've found that buying off brand batteries that are cheaper... is not money well spent.  Buy a name replacement or just put your money toward better tools.  I'm gradually replacing my Ryobi with Milwaukee at every birthday and Christmas.   

[novice]

Has anyone had any success reviving lithium ion batteries for power tools?

If tool pack uses 18650 batteries once they are dead they stay dead. The fix is testing each one and replacing the dud. The packs fail when one battery stop accepting the charge or discharges too fast. Liitokala makes a combined tester/charger that tests 4 cells at a time. It's also inexpensive and works great.

The issue comes down to the mechanics of testing & replacing bad batteries. Some packs are held together with security torx bits, others standard torx. Not a big deal but you need to buy a set. Next, remove all battery monitoring & charge balance wires. Take pics so the all go back in same order. Next, batteries are connected in series by nickel strips spot-welded to battery ends. You don't need a spot-welder but you do need a soldering iron, liquid flux (not rosin-core solder alone) and a quick touch to put packs back together. You manually pry off the spot-welded strip for each battery so you can test them.

Once you've found the dud you replace it with new one then carefully solder them all back together. Are you confident the remaining original batteries will continue to be OK? There are 2 brands I see thrown out all the time. Bosch however not one of them. But, that could also mean not as many sold. If are OK with reusing the old good batteries you need to buy a high-current 18650 battery of similar amp hours (AH) to replace the dud. Or, replace all batteries at the same time with higher AH rating. Better approach, they aren't that expensive, and you'll be confident about how long they last. There are good Chinese batteries whereas most Japanese & Korean good. Exceptions sure but consistency excellent.

As far as aftermarket battery packs, why not? My Milwaukee M12 can use a 3AH, 3X more than standard one. Branded it runs from $70 - $140, ouch! Bought a generic with 400+ positive reviews for $28. So far, absolutely no problem and would buy again. Had it about 3 months now, multiple charge/discharge cycles. So for me this was a viable alternative. I have also rebuilt packs for friends but it is time consuming even with the right gear to do it.

This video long but a good breakdown of process -

https://www.youtube.com/watch?v=91e9ZEGWulc&t=4s