Sounds like it's built-in internal battery is failing.
Without having a service manual in front of me, suggest you open it up and look for a "button" battery (like a big watch battery) some where on it's circuit board.
Hope this is helpful
Regards
John
Scanner Reset to initialize the scanner's memory, turn off the scanner. Then press 2, 9, and Hold while turning it on (It helps if you can lay it flat). The scanner will give you the option 'Restore Preprogram List? "Yes"=E/No="."', if you press 'E/Yes', the scanner reloads the preprogrammed systems.
Important! This deletes all programmed data.
Easier to Read BC346XT Scanner Manual
here is link to manual
their maybe a firm ware update but not sure as things change so does scanners do a search or uniden site helps a lot and radio reference. good luck
R&R2WAY
Hi, try going thru every channel in manual and see if any of them 'stay on'? Next, make sure that you haven't pushed the 'Priority' as that will go to that channel every second or two. Next, increase the squelch a bit so that you don't get a sudden burst of noise. and last but not least, keep this away from a wired Ethernet cable- putting mine by a CAT5 cable causes it to stop on two VHF channels. Good luck and let me know how it goes for you.