To georgetwo, Im not sure what you mean? I am using a car battery fully charged to power it up. It has 12V input. I have done this with others. I keep the battery well charged all the time.
To mramos1, There are no schematics available from harbor freight, I did contact them. Yes maybe I can troubleshoot it myself. I am just an amateur when it comes to working on electronics. I have done what you recommended with Google search. there are a lot of them out there, however I did not find much about fixing them.