The procedure to unseal the gauge to UNSEALED mode is as follows:
- Read the CONTROL_STATUS register and verify that the [FAS] and [SS] bits are set, indicating that the battery is in the SEALED state.
- Send the low-byte Unseal Key (the low byte is 0414; the default Unseal Key is 0x36720414).
- Send the high-byte Unseal Key (the high byte is 3672; the default Unseal Key is 0x36720414).
- Wait 100 ms.
- Read the CONTROL_STATUS register and verify that the [FAS] bit is set and the [SS] bit is cleared, indicating that the battery is in the UNSEALED state. If the [SS] bit is set, then return to Step 2. In this state, the fuel gauge allows data flash modification and complete operation of the UNSEAL state with the exception of modifying fuel gauge firmware or reading or modifying the security keys (Unseal Key or Full Access Key).
- Retry three times before stopping the sequence.