Batboard

HI all
I have GM350 VHF 128 channels - type: MD334BB
I have small issue with this radio - after two days of inactivity
when the radio is powered up the volume of audio goes almost to the full
and radio powering up on the last programmed channel (number 128)
instead LAST USED CHANNEL

Where may be the problem?
I saw that when radio is inactive one day (powered off)
that problem not exist.

Radio is programmed with option:
"POWER UP MODE - LAST CHANNEL"

Hello :
Just speculating here as I'm not sure but isn't there a Backup memory capacitor or battery on the bd that saves the last settings upon power down ?
Could it be the radio lost all the settings when the memory power went dead but chgd back up enough again to hold last settings when powered down for a day then back on ?
I'm qeussing here on this guys .
Satelite