I am in the same process now - replacing a Mudi battery because GL chooses to offer no solution. Thankfully they will be forced to offer solutions very soon, at least in EU and several other countries.
Meanwhile, in the real world, the original battery board: is it a standard BMS or something intentionally customized such that it would be hard to replace when building a new battery pack? I am trying to replace a Mudi battery but the old battery was mistakenly sent for disposal - meaning I can’t reuse the board or connector 