I recently acquired a Yamaha BBG4s as part of a trade but have realized that the bass drains battery even while I'm not playing. I researched it a little bit and found that my battery is probably not soldered properly to the input jack. Upon further inspection, I found that the black wire that comes from the battery is soldered to the top part of the input jack poorly and the small part near the middle of the jack where the white cable is connected too looks like it had been previously soldered but has no wire attached to it. I don't know if I'm explaining it well enough. But I have a photo. I have no experience working with electronics or soldering but I can get a soldering gun. If this is a simple fix, please let me know what I should do. I don't have very much money either and I wouldn't want to pay over $25 to get this fixed. Any advice?