Scart switching works by sending a voltage over Pin-8 to signal the TV or device to switch to that input. This basically means that if you have your Satellite on AV1 and DVD Recorder on AV2, the TV should automatically switch over to AV1 when you play a DVD (or turn the unit on) or to AV2 when you power up your satellite receiver. Just in case there is a faulty wire for Pin-8 in the scart cable, try swapping the Scart leads to see if this helps. Just note that only the top Scart connector on your DVD recorder should be connected to the TV. The bottom one should be connected with a separate Scart lead to the VCR/Aux port of your satellite receiver.
There is a possibility that you have had a different cabling setup before the renovation. For example, you might have had the Satellite receiver connected to the AV2 on your DVD recorder and then from AV1 to the AV1 socket on your TV. In this case, if your DVD recorder is powered off, it will simply pass the signal through, showing your satellite picture on AV1. Then when you power on your DVD recorder, it would take over and show its picture.