Did the lock-up occur after driving it? If so you might have air in the lines....as it get's hot it expands causing the brakes to apply a little, which then causes heat to be generated, which then causes the air to expand even more, etc.,etc.. It is a viscious cycle. People burn up (smoke) their brakes by not having the air bled out.
If it is a blocked return port, bleeding the brakes might let the debris get out of the port area and into the line (which isn't great to have debris in there but at least you can move the thing). I have used a turkey baster to suck the old fluid out of the fluid resivoir, refilled with clean new fluid, and then bled each corner until it ran clear. This is the simplest form of "flushing" the brake lines that I can think of. You could disconnect a line near the cylinder, but the brake fluid acts like a paint remover so you'd have to be carful of where the fluid went, AND you would have to bleed all four corners anyways (to make sure no air was in there).
