P0720 code with no speedometer or cruise

I have a P0720 code and non working speedometer on my car since buying it. I pulled the instrument cluster and repaired the notorious "cold solder" on the back that fixed the tachometer, but still have the code and no speedometer. I have also noticed cruise will turn on but not engage, most likely due to speedometer reading "0". I replaced the output speed sensor for the P0720 "Output speed sensor circuit malfunction", which made sense, but did not fix anything. I then replaced the input speed sensor since some people claimed this had fixed their P0720. I took car for a drive and not only did it not fix anything at all, but the transmission would not shift. I put the old input sensor back in and transmission shifts, but original issues still exist. I do not have the information to check the harnesses, not to mention getting down to the connectors with testers will be a challenge. I do not know if the cluster is still an issue, or if wiring/computer is faulty. Maybe try another new input sensor?