Omnia II Charging Blues

[Guest Always_Learning]

My Omnia II will not charge with some 12v dc (red charge light will not come on), wall plug and some USB chargers.. It seems to vary all the time whether the unit will charge or not.. Some times I have to power off the unit and charge it that way overnight. What do I need to do to make sure it charges at ANY time? Have searched the forum but have NOT found a definitive answer to this issue..