Hello there. I am having engine/transmission problems with my Volvo XC70. Earlier today I got in my car to start it and at the same time I started the ignition I simultaneously changed gears from park to reverse. Essentially, I started my car in reverse instead of park. This led to a sort of clicking noise and a "check engine light'" on the dash. The car won't turn over and every time I start the ignition I get the clicking noise and the light. The clicking noise sounds similar to the sound a dead battery but is more "clunky". I am able to shift gears but unable to start the car. I have attached a video to this thread which shows the engine and the clicking noise which is emitting from it.

 

You need to scan for the CEL to find the fault code. Did you try a jump start to see if anything changes (and to rule out a weak battery/cable issue). The shifter has a position sensor (google "Volvo PNP switch") that tells the ECU where the shifter is - normally when functioning properly you'd only be able to engage the starter with the shifter in Park so something is either broken or needs adjusting in the PNP. Next time it fails to start, try doing a "shifter row" (move the shifter from park to lo to park 10-20 times fast). then try starting again. This can clean off the contacts in the PNP enough get it to behave, but if not, you'd need to replace.