My bet is if you have Brembos, there was corrosion under the stainless sliders, which pushes the edges inwards, resulting in less space for the pads to move, so they're grabbing all the time, can't release & is building up heat. Sounds like they'll need to grind the edges of the pads back so they slide freely.. Very common issue on 4 pot Brembo calipers. Apart from a strip down & removal of the sliders this is your only option. I've had to do this on loads of Brembo calipers I've worked on.