Power to the Motherboard problem or just Battery needs changing

georgeelias1950 measuring a battery with a multimeter will only show you the voltage of the battery but it will not show the condition off the battery. Even a battery that shows the proper voltage may have failed if it does not supply the amperage required by the device. To determine that, you will have to put a load on the battery and measure the amperage. Not an easy task on the type of the battery for your GPS. I suggest that you start by replacing the battery regardless of what voltage it shows. If nothing else, it will provide you with a known-good point if further troubleshooting should be necessary