new to me 2004 hummer, battery light stays on
 

tried the battery cable trick, light still on with engine off, any ideas? I did have to boost it and the light stays on since then. any help please

sounds like the alternator has craped out. I would take it to have it checked.

It sure does sound like the alternator. You should forget the old battery cable trick. It's a good way to send a voltage spike to some expensive electronics.