L-NAV problem

The L-NAV in my new to me ASW20 is not functioning properly.

The unit will shut off and re-boot randomly. It does not happen every
flight, sometimes will happen only once and then stop and other times
it just continues to shut off and re-boot.

I am about to pull the unit and replace the internal battery. Any
other thoughts or actions?

I have put a new battery in the plane, voltage readings according to
the L-NAV and GPS NAV have always been north of 12.5 volts. I have
inspected the wiring nothing is obviously frayed or shorting out.

Thanks in advance

Ron Gleason