Had a leaky rear cylinder, so I decided to have them rear drum done, new cylinders, etc.
Brakes work great, but the warning lights will not go out unless I press hard on the petal, but they come back on after I release it.
Have had the lights come on for a day or two before when the fluid got low, but they always went back out.
What should I look into this time?

 

Take it back to whoever did the work and make them fix it.

 

Take it back to the shop and have them fix it like jkeaton said, but generally this is because the ABS valve is seeing incorrect pressure. Probably from air in the line. If they replaced one wheel cylinder and not the other, without bleeding properly there is probably air trapped in there.

I rebuilt the entire rear brake system and went through a whole bottle of brake fluid bleeding them. Haven't had an issue with the ABS light coming back on yet. To keep that light off, bleeding the system well is key.

 

"had" the brakes done/ possibly 1st mistake. nobody touches my trucks but me.