Followed the directions and the build plate system was DESTROYED before teh first test build.

[George Simpson]

I bought this system for my old Monoprice printer to update away from the

masking tape and how strongly stuck my prints were.

I applied the cleaned and level the original build plate and applied the magnetic build plate.  Placed the buildtak sheet to the flexplate and placed it on the new buildplate surface.
I then calibrated by Z axis, like I have always done for PLS, with a piece of card stock and start by test print.

The printer warmed up the bed to 60  C and then the extruder to 205 C and the print started.  Instantly where was a loud screeching and grinding I saw the flex plate being drug all over the build plate and the nozzle had burned completely through the buildtak sheet to the flexplate.

My first thought was I didn't have the nozzle gap right on the new stuff, so I rotate the flexplate (to move of the burned spot), calibrated my Z again and then raised the xozzle sightly so it's further removed from the plate.  The exact thing happened. 

Third try, same procedure, but I raise the gap to a metal credit card, 0.8 mm, and there is a lot visible daylight between the nozzle and the build plate.  Same thing AND now I notice the metal build plate has also been melted though.

Has anybody, including buildtak, had this system work with a monoprive mini?
Why would hte print head (I think it was the nozzle) catch and drag that flexplate around when they where never touching?

The new build plate is adhere so strongly to the old plate I am worried I will have to replace the original to get to a known-good configuration after this grabage.

[Will Phelps]

that has to be frustrating. I don't own a monoprice, but I do own a couple of MakerGear M3's.  I've been using the Buildtak system for years now without problems.  I calibrate the z-height using a card stock and it works every time. 
Not sure but from what you wrote it sounds like you are doing the calibration and then heating up the bed and extruder - that would be problematic if so, both should be at the normal operating temperature before attempting to set the z-height. 
I hope you figure out what is happening!