New Rear Brake Pads -undrivable 380 Degrees

I am sitting at home this week end. 1994 N* not drivable.

Friday professional mechanic installed rear brake pads on Deville concours w disk brakes ABS.

Wagner thermagard the best avail from Auto parts store. They had four different qualities

I drove 1.5 miles stopped and smelled what I though was electrical insulation. I was very wrong.

I used a laser heat gun tool to read the temp. Left Rear wheel was 380 degrees and Right rear was 145 degrees. Then I reached down and touched the hot wheel cover with my finger, proving that You don't need to spend money on every neat tool that becomes available.

Drove right back to repair shop at closing time. I am thinking incorrect installation. This was to be a simple pad replacement.

Monday morning we will find out.

However I would like to hear from any on the forum that may have some experience w this brake scenario.

Could a brake caliper decide to act up and not allow piston to retract? I visited the O'Reilly Auto Parts store to look at a caliper and the installation instructions( i.e. package insert) The instructions warn about damage to old caliper during removal ( they need orig. old parts not damaged ) AND big time warning about the Parking Brake (a.k.a. Emergency Brake) Adjustment
the gist of the message was if you experience premature wear of brake pads it could very well be mechanic's failure to adjust the P Brake cables properly and not the part you purchased from us.

This car was wrong when it came off the lift, problem evident in 1.5 mi of driving, What could have gone wrong with a simple pad replacement?

regards