First battery build, help requested!

Hello All, I just built my first battery pack 2170 cells in 7s14p config. I individually verified all cells were at the same 3.62 resting voltage before beginning the build.

As far as I could tell everything went to plan, and after all spot welds were completed each 14p group was measuring the same 3.62 volts and the total pack was right around 25.3v.

After two days of sitting inside a pelican case with all conductors well insulated with non-conductive tape and head shrink cell number 5 completely discharged itself down to 1v. the other 6 cells are still sitting perfectly at 3.62v. I pull off all the heat shrink and can find no evidence of a short, nothings melted to indicate a rapid discharge, and no swelling I can see to indicate…

Any and all troubleshooting advice would be greatly appreciated.

Thanks for you time!

Did you use fishpaper rings? Post detailed high-res photos of the battery and the battery inside the case.