I decided to replace my front brake pads since they are worn out beyond function. So after removing the old pads, I made sure the piston was fully out, and the adjusting screw was fully tight as well, and still I could not get both of the pads in. I can get only one of them in perfectly so I do not doubt a compatibility issue.
I decided to take out some of my worn-out brake pads from the rear brake so at least I would have some braking power in the front but I could not remove the rear brakes because they were also too thick to get out. What other options do I have other than manually opening the caliper in half?