KEYSIGHT 1252b not reading voltage ranges up to unlimited voltage

[FF1776x1]

I have a keysight 1252b and it won't read voltage correctly when I apply voltage it just ranges up then starts beeping . If I temporarily apply 3 volts or so it will climb to unlimited voltage until voltage removed . I think the beeping is the over voltage alarm because I see it climb and go to 1000 almost instantly and start beeping . I tried to turn on filter in settings and it does the same thing . Took it apart all components look in good condition no visual damage . What could be causing this ? What boards or components should I target for repair/test ? Are any firmware updates out for this model ? Thanks for any help

[Kleinstein]

This does sound like a serious problem, like an amplifier working as an intergator instead of amplifier. This could happen when a feedback resistor is lost / disconnected.
Another problem could be a similar failure in the ADC.
The problem is that chances are that all this is internal to the central chip. So chances are high this meter is beyound repair.

Are at least the current ranges and maybe AC working OK ?

A first usual check are the batteries - best case just the low bat check failed, though it is unlikely a low bat would cause such symptoms.