So Just today i installed a car head unit [nav system] at a shop and he installed it but the speedometer has stopped working i dont know why i went back to the shop but the guy said even he doesn't know why he checked the fuses and all seems to be fine it worked perfectly before installation he tried to disconnect and then asked to drive and yet it did not work can anyone help me with this or what is the going the guy refuses it was his fault and blames that it was a previous issue it got late so i came back home i will go tomorrow again to fix it but till then if some has faced this issue before or know what this issue please reply to this thread

Model: Pajero Sport 2012
Nav System: lenovo D1