Rotors---Yes---Too HOT if they were glowing---warped is more than possible---Likely---Not worth keeping.

Calipers---MAYBE---But probably not, if they are "free" and moving---You did NOT help them any---not at all, but you may not have killed them---Brakes are MADE to take heat---The pads and rotors would have generated the heat and soaked most of it---The question is how far did it go up the system---from what you said, I would guess NOT FAR enough to kill the calipers---AGAIN if they are free and moving and mileage is low, you should be okay.

Master and booster---NO, I doubt these are in play---These would show problems with the fronts too---No pedal or hard pedal but not a locked rear---Bad masters usually mean NO PEDAL---I have never seen a booster do anything like this---The booster is just the power assist part and means HARD PEDAL---The heat did NOT get to these parts---Chances of BOTH are near zero.

What sensor?---Need to know this.

Pads---Yes---same as rotors---with that heat not worth trying to save---Glazed, hard spots and/or heat cracked is my bet---Maybe all three---They need to go.

"fuel line flush"---Do you mean brake line flush?---If so---Yes---Should be done every 25k anyway and again with the "heat"---DO IT---You can boil brake fluid.

Locking JUST the rear could have been a proportioning valve or problems with the ABS (do you have a "light"?) or a few other things---Nothing I see here would be limited to JUST the rear---MUST FIND CAUSE to solve the problem.

Having TWO "bad" calipers lock-up at the same time out-of-the-blue would be lotto odds---same with two bad rear brake hoses---Could happen to you but so could being hit my a meteor while reading this---Possible but not probable.

Ask him---What caused the locking?

Is it "free" now?---If so---WHY?

Still need the mileage on the car.

Sounds like a shopping list to me---He may be honest---I am not saying that he is not---He may be "lost" and just replacing "everything" like you said---Not knowing is not the same as lying, although BOTH will cost you about the same---Does not sound correct to me.

Hopeful others will jump in.

Let us know, Jimmy