Option key works by chance only

Install OS (MacOS Lion or Windows 7) in MacBook Late 2007

Hi,

I have a Macbook Late 2007, white body, with a Core2Duo processor, 2.5 GB RAM, and 500 GB Hard Drive.

I have realized that my option key only works bye chance. It doesn't work at all, except at the lucky times only.

Lately, I changed the Hard Drive, and messed up with the OS, so I don't have anything running on it right now. I have visited a number of forums, but couldn't get an answer to my issue.

My first issue with this MacBook is that it does't show any options on pressing the Keys if it doesn't have an OS. It is unresponsive to Cmd+Ctrl+P+R, Options Key, Cmd+S, Cmd+S, Cmd+R, Cmd+T, S, R, T, or any other shortcuts (I could find on internet) which you could use to access the Booting Options in a MacBook. You start the machine, it gives chime and a white screen, after sometime it gives a Circle with Cross.

Tried booting from USB, and CDs. I made MacOS 10.7.5 (Lion) which was working on it, but it just does not boot up. So my major concern is this, that my device is unresponsive to any and all the shortcuts. Last time I got the OS installed from an IT Shop, and the guy took out the hard drive, put it in another MacBook, and installed the OS. Now I don't have that option, plus I don't want to spend money on that since it is a spare laptop.

My second issue is that with this condition, is it possible for me to install Window 7 on it? I couldn't find a step by step procedure to do that, if someone could redirect me to a link which is helpful. I completely understand this can't be done till my first issue gets resolved. Even then, I am not sure if MacBooks boot directly from Windows 7 USBs.

Since the time this issue arose, I have been able to install the OS once when option key worked by chance. I ran bootcamp, the setup interrupted, and something happened, as a result of which, my Macbook now gives “No boot device". I have connected that hard drive externally and the drive is perfectly fine. I am again at that stage where I can't install the OS from USB again. What should I do now?

I would be really thankful if someone, who has done something about this, could help me around it.

Best,

HAJ