I’m a little lost on trying to trouble shoot this one, any advice is appreciated. I purchased a 2 ton single head Daikin minisplit system online a few months ago to install in a workshop in my backyard, that I’m in the process of renovating. Everything was going smoothly with the install, doing the majority of the work myself. I am a builder by trade and have done several minisplit installs over the years. I hired an HVAC tech to connect the refrigerant linesets, and evacuate/ pressure test the lines. As far as I can tell the problem came about when I connected the wiring. Unfortunately I crossed the signal line and one of the power lines at the outdoor unit control wiring. When I went to fire up the system, the indoor unit status light started flashing blue, indicating a system error. I realized what had happened then and corrected the wiring. No luck, still flashing blue. Error code retrieval at this point, at the remote control reads U4: communication error. Next I tried pulling the outdoor unit control panel to see if there is a blown fuse. I was able to locate 3 separate fuses but none of them tested bad. Pulled the indoor unit control board and there is one fuse which also checked out ok. Last I try running a separate jumper wire externally to eliminate the possibility that there is an unseen break in the original signal wire. I then try turning the system on again, same thing: indoor unit status light flashing blue and error code U4. Any ideas?