Occasionally the LI-250A Battery tabs can become depressed against the sides of the battery compartment. When this occurs, the battery may make intermittent contact with the tab, especially if it experiences a fall or hard landing. The temporary loss of power due to intermittent contact with the battery tabs may then cause the processor to lock up and the instrument will cease working altogether.
To resolve battery tab problems, gently bend the battery tabs (below) until the nine-volt battery fits snugly into the battery compartment. The battery should not fall out if the meter is turned on its side or upside down.
If the processor does lock up, remove the batteries and wait five to ten minutes for the processor to reset.