a month back i had a crash where the brake lever got a clump of sand on it, so i washed it out with water and didn't have any problems, then one random day when i took my bike out for a ride i noticed the brake lever is significantly stiffer then usual, and that the pads are in hard contact with the brake rotor, i tried pushing the callipers back in, but had no affect. because before this, 70% brake lever movement was when the pads arent touching the disk, and the other 30% where your actually braking... now its 100% brake, because the pads are in constant contact with the rotor, such hard contact that it squeals when moved. (Shimano saint, if that helps)
Edited - Missed that he brakes are Saint.
I have had this occur with a different brand of hydraulic disc. The lever has a valve that closes when the lever is pulled in, sealing the system so the hydraulic pressure builds and drives the pads, and opens when the lever is released, allowing the system to balance as things like heat cause fluid to expand. In my case, this valve was blocked, allowed fluid into the system but not out, jamming the brakes on. I ended up replacing them with Shimano's
A more common reason for this is the brakes have been bleed and overfilled.
I would start by attempting a brake bleed. If the fluid will not travel up thorough the lever for a bleed, disconnect the hose and you can find out if the blockage is in the lever, hose or caliper. From there, the blocked part can be serviced, or the bleed might fix it.
The crash may have bent something that is not moving freely, but otherwise its hard to explain the symptoms. A possibility is dirt, or the lever is bent, stopping the lever going into its full open position, so stopping the internal valve opening to release fluid into the reservoir.