Try pressing the rectangular looking "blue button" near the top of your keyboard. I have an old IBM ThinkPad T40 (using right now) from 2003, the button is called "Access IBM". I'm not sure what Lenovo calls it, but during the boot up process it should bring you into the Rescue and Recovery menu. Perhaps, there are some diagnostic tools there to help you figure out what the problem is.
I only used the "blue button" on my ThinkPad T40 when I want to do a fresh re-install of Windows XP or to access the BIOS.
Try giving Lenovo's tech support a call. I don't know what their warranty period is, but IBM's warranty period was 3 years standard back in the day.