Buttons intermittently not responding, screen fade un-fade from perimeter (looks brown). Factory reset, worked little while then the 1/2 full rechargeable battery died. Switched to the alkaline (1/2 full) AA battery pack. Finished hunt but still had minor issues with the screen. Etrac and original rechargeable battery over 7yo. Bought new Minelab NiMH 1800mah thinking this will solve the problems. Any insight on diagnosis and battery solution for issues?