Hello, help ,I installed a 3 ton unit heat pump and air handler (goodman 13 seer),When I tried to install the new thermostat I think I touched the wires and burnt the transformer, when I replaced the transformer and turn the unit on it keeps blowing the fuse from the circuit board on the air handler , I noticed that When I disconnect the red and blue wires from the outside heat pump the air handler starts and it does not blow the fuse, did I messed up the circuit board or I wrongly connected the wires ? Help!!

You need to track down the low voltage circuits and see if you have a short or a defective component. That is the only way to know for sure.