A Hangzhou customer found him on Xianyu, bought three 18650s himself and asked for a swap; thought he'd have taken it apart but he hadn't, 'lost out on that'. Screws out and the Xiaomi shell is still clipped on really tight, the clips won't prise off and snap as soon as you try; more or less got the battery out (XCJ002 MB_26_240311 three-cell pack). Old cells read 1.2/0.7/1.8V; RC3563 tester puts resistance at 14/15/16, 'not actually dead, they just need waking up'; but the customer bought cells, and if you don't swap them he might get ideas, and if the swap doesn't work it's not on me; do the new cells need balancing? new ones are generally fine; the new cells' resistance is higher than the originals', 'useless', but no big problem, fit them anyway. Get the AWithZ soldering iron — no, spot welder — out, gear up to 40; 0.15 nickel strip feels weak so 50; can't tell which gear is right so 70, worried it won't hold so higher still; welds beautiful; each original strip had a little tab soldered to the board, no such tabs here, should have prised the small ones off, without tabs just hammer flat and weld on, 'tell me if I'm doing this right'; feels like the welds are big; weld one corner solid then flip; clean up the pads and board, fish paper along the edge for protection. It was actually fixed, but the cells got wired wrong when connecting (even with photos): drew it out and found the + − + alternation had two negatives together, a friend pointed out that if this side is negative the other can't be negative too; strip and rewire, one side positive one negative, 12.6V now right, fully charged, fixed; lucky it was wired to the BMS, the main unit would have burnt out; from now on take clear photos. Comments: 20mΩ is quite normal for capacity cells; no need to strip it, just wake it with an adjustable supply; why is each cell's voltage different (quite normal); low resistance doesn't mean a good cell, no voltage means it's dead; you're hilarious, greener than me; brute force works miracles.