first question is a Hobbyking or other MinimOSD clone or genuine 3DR(I just had a HK clone break in exactly the same way, there was no fixing it, replaced with a clone from multirotor superstore).
This seems to work a bit better but polarity of pixhawk connector seems to be reversed.
If 3DR then call customer support and open an issue for a swap out… 3DR is very good about supporting their parts for the IRIS .
let us know how it goes…
hotel zulu lima...
ps try loading the charset for the OSDconfig,hex,charset combo you are using before doing anything… use the OSD_config program in windows to load same with a serial adapter…