Zoom H4 appears to be shorting out

Hi all,

I have a ZOOM H4 Handy Recorder (the older model, I got it in 2009), and it has suddenly decided to start having electrical issues. This is particularly bad timing as I have a string of interviews coming up, and my iPhone just isn't a suitable substitute.

Here's what's up:

When I put batteries in the machine and close the lid, it drains the batteries in less than an hour, and it seems to do so whether or not the machine is switched on. Additionally, it feels a bit warm—overall making me believe it's a short.

Also, the machine sometimes doesn't function. If I fiddle with the battery cover, current ir restored and the screen turns on. The contacts on the inside have some corrosion. I tried cleaning them, but the short remains. In addition, the metal between the two contacts appears a bit darkened.

Two questions:

1) Is it a short?

2) How do I fix it?

Thanks!