This applies to several S40 model years up to about June 2007. There is a break in the 2007 production year when the cars were slightly updated around July of that year. The procedure is different for them. This may also apply other models that used the AW 55 transmission.

The car came to me with the automatic transmission stuck in neutral. Looking at the base of the shift lever it was obvious the shifter blind was missing.
https://store.voluparts.com/volvo-s40-shifter-blind/

When it breaks up the car does not know what gear it is in and will not let you shift or remove the key. Disconnecting the shift lever cable from the transmission will let you shift the gearbox into park and remove the key. When the lever on the transmission (that the cable attaches to) is all the way forward it is in park.

Remove the bezel from the central flat screen display. Reach behind it with a 90 degree pick and pull on the top two corners. Tilt the top out and remove the bezel. Same with the display. Disconnect the two wiring connectors. The are two 25 torx headed screws that are now accessible. Remove them.

Pop out the 12V power point that is directly behind the shift lever. Two more torx screws are visible. Remove them and the center console is loose. Unplug the wiring connector and set it aside.

Remove the shift lever by prying down the plastic collar below the shift knob. The bottom of the shift knob has four plastic fingers that engage in a circular groove in the shift lever shaft. The collar has to be clear of the knob to let the fingers release. It will help if you lift them slightly to clear the groove. You may have to find a place on the shift gate that will let the collar go down far enough. The gate is held on by four little tabs, one on each corner. Pull straight up on the shift knob.

The circuit board at the base of the shift lever is held on by two small tabs, fore and aft on the drivers side and two larger tabs on the passenger side. Poking them with a pick will release them.

The busted blind will be spread all over around the base of the shift lever. Remove as much as you can. There is a little silver rectangular magnet that is stuck to the shift lock mechanism on the forward drivers side. Be careful not to dislodge or lose it. Lay the new blind over the shift lever. The corrugated side goes down. The rectangular opening on the cross piece goes towards the drivers side.

Now the transmission can be shifted. Put the lever in park and reconnect the cable at the transmission. Reassemble everything being careful to get all the tabs locked. The collar on the shift lever will need to be below the fingers on the shift knob so they will drop into the groove on the shaft.

The second time you do it, it will take 20 minutes.

Greg