Problem with the backlight of the CME dt-9939 multimeter display

[krysjaz14]

Hi
At the outset, I apologize for the language. I am an electronics beginner, I recently bought a used CEM DT-9939 (version DT-9939-9) multimeter and I have a problem with the display backlight and the low battery icon is still displayed despite the new battery. The voltage on the LED comes to 4.4 [V] when the backlight is turned on. I replaced the transistors but the problem is still there. As I look, you can see it on a different layer as it would be powered directly from the battery plus but I'm not sure. In addition, this battery level constantly signals discharge.