Typically, batteries in new devices of the same type can swell for the following reasons:
1. The layout is too dense. If components are located very close to each other, the battery may become pinched or subject to mechanical stress. This increases the risk of physical damage to the battery and may also cause it to overheat due to heat buildup from nearby cells.
2. Incorrect charge management. The charge controller may be configured incorrectly, allowing the battery to overcharge or deep discharge. Without correct voltage and current regulation, the battery overheats and is subjected to increased stress, which leads to swelling.
These problems often arise due to insufficient testing of the prototype device under various conditions or flaws in the design stage.
It would be better if Ledger made wallets with replaceable batteries like the Passport or Coldcard Q.