When the battery runs out, the device will permanently lock and delete all secure data (note: this only applies to devices where the tamper mesh is armed - if you want to safely store your Lattice for some time without using it, you can backup your Lattice wallet, remove your Lattice wallet in the Manage Wallets menu, and disarm the mesh. You can then restore your wallet and re-arm the mesh when you start using the device again).