Tacho defect Fiat Punto Sporting 188

Hello together, I have for 2 days the following problem with my Punto Sporting. So he stood over Christmas 2 days when I wanted to turn it on you already noticed that the battery is difficult, is still the first and at least kept 8 years. When he had then jumped I drove extra a longer distance so that it was again fully worked. Then stopped and went shopping, put in and then eater really just started again. So immediately started On the way to the car parts dealer then my speedometer started to spin. At 70 kmh he started to twitch and is at zero. Next time he didn’t want to start at all. So the needle only twitches, but always stays at zero. New battery built in (now it starts again super) but the speedometer is still dead. The kilometer counter Funzt however still as well as everything else in the instrument cluster so control lights, temp, tank, speed meters I don’t know if the thing with the battery has anything to do with it that he doesn’t want any more. Therefore, my questions: What does the instrument cluster cost at Fiat ? I found some combi instruments on Ebay although not from the sporting but white dials don’t have to be if the part is new to expensive. Can I just expand the old one and exchange it for another or do I have to go to the workshop ? Are there only seven screws if I have seen correctly. Hope you can go far away from me . r Help Greeting Mike