I have a ton of these things, and they are all bad. I’ve opened at least 20 and tried about anything one can imagine, and am usually good at finding a battery fix except for these and Ridgid batteries. I’ve come across a few different issues, sometimes it is the temperature sticker that kills the circuit, sometimes the sole capacitor is blown, sometimes it is just one of the rectifying capacitors, or sometimes there is no apparent flaw in the battery. I’ve tried giving it a boost, I’ve tried balancing the cells, and the only thing I’ve done that works is bootlegging the negative out past the firmware and soldering it to the last cell in the parallel (2) 20v batteries. The major catch is while it will charge, and discharge, it will catch fire because it doesn’t know when to stop taking a charge, you have to charge for no more than 30 min, and let it rest for 30 min. Not a real fix. Similar to Ridgid batteries, except you can get lucky and solder the bad and good rectifiers together to complete the circuit on a Ridgid without issue and it continue to work as it should. But with the 40v, just throwing bad signals out constantly. Anyone have a clue or recommendation on what I might be overlooking?
I can’t help you with the 40v problems but if I’m not mistaken the Ridgid and Ryobi 18v batteries have identical components on their boards(obviously different shape and physical layout) and repair methods are interchangeable, so while googling your Ridgid battery problem just change the name to Ryobi and vise versa.
Thank you for your insight, sadly the Ridgid batteries have some slightly different firmware that the new metered Ryobi batteries have adopted. The p102 are super easy fixes, but it can be a crap shoot on the metered batteries. The Ridgid seem to have an issue with the rectifying capacitors, there are 2) 40v capacitors ran in series so that if one goes, the circuit is broken. At times one can bridge these for a fix, but not always. Wish I knew more about electronics.