is bloated, expanded, swelling or otherwise deformed
has any cell with a voltage of 3.3v. This means less than 9.9v for a 3-cell/11.1v battery.
Do not charge batteries unattended. Monitor batteries during charging for popping, hissing, smoke, sparks or fire. Also monitor the battery for any swelling or other deformities. Disconnect the battery from your charger immediately.
Do not charge batteries near flammable material. Charge batteries in a fireproof container. Do not charge batteries while they are in your robot.