Welcome, I am Chris (aka-Moose)
Open the bleeder screw on the locked up calipers. If the caliper will not release the pressure on the brake pads then the caliper piston has seized. Possible causes for that are old worn out brake fluid that should of been flushed prior or the incorrect pads are used and they are getting to hot and transferring that heat to the calipers. If the calipers do let go with the bleeder open then suspect a master cylinder or ABS hydraulic control unit issue holding pressure to the caliper when not needed.
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