All 4 brakes seized up, help

[btrux0611]

Hello. So I'm a long time mechanic. First time seeing this problem. So barely made it to my shop, and the left front brakes pads were on fire, a little. Then noticed all 4 rotars looked like cherry red. Now I've seen this happen a few times on one wheel, not all 4.
So we cracked each bleeder to get the car to roll finally. Front brakes are toast of course.
So what's the cause? Master cylinder or abs module?
Brake fluid hasn't been touched and I drove it a couple hundred miles recently. I did just buy it broken down a few months ago ( timing belt failure) but the brakes were all fine.
I did find that the first time and tried pushing the right front caliper piston back in, it was frozen. Then ironically my friend started pushing the brake pedal and it did start going out, then I was actually able to seat clamp the piston all the way back in normally.
Any ideas? Could one front caliper locking up cause all 4 to over heat and drag heavily? Old brake fluid simply boiled over, expanded and heavily dragged/ seized all 4 calipers?

[abscate]

Probably just all four corroded and not releasing. Once they get hot it goes downhill fast

[volvolugnut]

Try to bleed/flush each wheel caliper. If you get brown crud or no flow, plan to rebuild or replace each caliper. Then do a full flush of the complete brake system.
volvolugnut