SD1 Warning message

Hi, I am toataly new to this forum and asking this question for someone else.
My nephew has, by way of gift, accuired a SD1. It was given to him in non working order. When powered up a "Warning - Battery Voltage Low" message comes up, along with Save Data, See Manual and "continue". Pressing the continue button does nothing.
Is there anyone out there that can offer any suggestions on what maybe wrong and how to remedy this problem?

There is an internal battery in the SD1, that needs to be replaced. The battery cost is under $5, but a service tech will charge around $45 to replace it..
They usually last upwards to 10 years..

Thanks for the prompt reply. I can only hope it is something as simple. Do you know if the battery replacement is user friendly?

Yes, if you are technically inclined..