Found fuse to be open. Put little Popper breaker where the fuse goes. Tested all operation to see if I could get the fuse to pop again. found the outdoor unit not coming on. Said had an 05 fault which was the board. Reset everything try to make it start. I had 24 V coming into the board check high pressure low pressure. Both safeties were closed. Then I started getting a low pressure fault. So I put jumpers across it. Still got default. Try to reset the fault it was stuck. Defrost board needs to be replaced.