probably you know it, but one output is DC, while the other is AC.
If it's not the power supply, you can try quickly switch it on/off. I have this problem on a C64C and it will boot up after a while (probably a defective/tired chip).

If not power supply, usually it's the PLA chip and sometimes the VIC-II or RAM or Character ROM are shot. Most of the other chips stay solid. Check lemon64 or google to diagnose the symptom properly. I think lemon64 gets more traffic than chipmusic fir these types of issues.

SD2IEC. Sd card drive for c64.
It's a machine. You can repair it depending on how much time and energy you want to invest. You can find people who will fix one for you. You can buy a tested, working one...
People sell small c64 power supplies on ebay and ray carlson sells massive hardcore ones.

I tested the power supply. The 12 volt pin is outputting about 5 volts and the rest nearly 0. That's a problem right off the bat.

A few years ago, I bought a Commodore 64, for the heck of it, because I saw it at the local flee market. It's fine to look at. But now I make chiptune, and really want to actually do something with it. The power light comes up. When I plug it into television screens, I see more than tv static, but I don't see the C64 console. It's just black ,with static in the corners, and some random colors.

I'm willing to bet that it was sold to me not properly working (at least I've got some use from the joysticks). I wonder if there is anything I can do to repair it?

I'm also wondering how I can go about playing the rom files from my laptop back to the Commodore, to load programs.

Any suggestions?