Spider brake job

[Fiatnut]

I have a question in regards to a brake job I had done to my 79 Spider .At the end of last summers driving season I noticed my rear brakes sticking so when I pulled the car out a few weeks ago I decided to change the brake rotors ,pads and have calipers rebuilt.This week with about 40 kms put on the new brakes I get a four wheel lock up on the highway completly de-mobilizing my car cooked all four rotors pads and burst a flex hose the other three lines were ok.I was told by the rebuild shop when picking up my calipers that the last guy who did these did them wrong something about a washer put in backwards. Any information on why this happened would be great?

[So Cal Mark]

if indeed all 4 calipers locked up simultaneously would point towards a master cylinder issue rather than the rear calipers being assembled incorrectly

[Schnauzer]

would have to be pressure build up in lines and in this case two separate systems (F & R). Only thing that would conceivably do that is heat explanding the fluid which if DOT 3 would not happen. If someone mistakenly used DOT 5 which is silicone this is theoretically possible