You may want to revert to an older, more stable build or force an upgrade when OTA fails.

The easiest way is using function. You can read each partition to a .bin file.

If you only need to clear settings or data without a full flash, you can use the factory reset code: NOKIA 105 DS TA-1034 NORDICS WHITE - Multitronic.fi NOKIA 105 DS TA-1034 NORDICS WHITE - Multitronic. Multitronic Nokia 105 (2017) user guide: Restore factory settings - HMD

Unzip the downloaded firmware and tool onto your desktop.