Yamaha V50 help

[SneakyGuacamole]

Hi,
I recently bought a Yamaha V50 on criagslist and i'm having some trouble.
All of the Keys C3 and above make a strange drum noise when I play them, while the keys below C3 are silent. The drum noise is persistent even if I use a different sound.
I tried loading the demo sounds on the keyboard, but they go away if I turn the keyboard off and then on again.
I've also tried a factory reset, but the keyboard doesn't respond to pressing the three buttons.

Any suggestions/tips? Right now, I'm thinking of replacing the internal battery, but I'm not sure how easy that is to do.

Any kind of help is appreciated,
Thanks

 

[Beau]

I am having the same problem. a company called syntaur (couldn't post a link) looks to be the place where a battery can be purchased for $7. Good luck, and let us know how it goes. I'll do the same!