Originally Posted by op
I removed the tstat face, loosen all wirings and connected are to why & G at the same time, turned on unit, fuse blew.
Happened. It's not the tstat.
It still looks like a wiring fault. Next you need to isolate, is it why or G that's causing problems. Just like I asked you to do earlier.
Check why & G independently.
Do you own a multimeter?